{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2021-46939", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-02-25T13:45:52.721Z", "datePublished": "2024-02-27T18:40:27.471Z", "dateUpdated": "2026-05-11T13:44:49.866Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-05-11T13:44:49.866Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Restructure trace_clock_global() to never block\n\nIt was reported that a fix to the ring buffer recursion detection would\ncause a hung machine when performing suspend / resume testing. The\nfollowing backtrace was extracted from debugging that case:\n\nCall Trace:\n trace_clock_global+0x91/0xa0\n __rb_reserve_next+0x237/0x460\n ring_buffer_lock_reserve+0x12a/0x3f0\n trace_buffer_lock_reserve+0x10/0x50\n __trace_graph_return+0x1f/0x80\n trace_graph_return+0xb7/0xf0\n ? trace_clock_global+0x91/0xa0\n ftrace_return_to_handler+0x8b/0xf0\n ? pv_hash+0xa0/0xa0\n return_to_handler+0x15/0x30\n ? ftrace_graph_caller+0xa0/0xa0\n ? trace_clock_global+0x91/0xa0\n ? __rb_reserve_next+0x237/0x460\n ? ring_buffer_lock_reserve+0x12a/0x3f0\n ? trace_event_buffer_lock_reserve+0x3c/0x120\n ? trace_event_buffer_reserve+0x6b/0xc0\n ? trace_event_raw_event_device_pm_callback_start+0x125/0x2d0\n ? dpm_run_callback+0x3b/0xc0\n ? pm_ops_is_empty+0x50/0x50\n ? platform_get_irq_byname_optional+0x90/0x90\n ? trace_device_pm_callback_start+0x82/0xd0\n ? dpm_run_callback+0x49/0xc0\n\nWith the following RIP:\n\nRIP: 0010:native_queued_spin_lock_slowpath+0x69/0x200\n\nSince the fix to the recursion detection would allow a single recursion to\nhappen while tracing, this lead to the trace_clock_global() taking a spin\nlock and then trying to take it again:\n\nring_buffer_lock_reserve() {\n trace_clock_global() {\n arch_spin_lock() {\n queued_spin_lock_slowpath() {\n /* lock taken */\n (something else gets traced by function graph tracer)\n ring_buffer_lock_reserve() {\n trace_clock_global() {\n arch_spin_lock() {\n queued_spin_lock_slowpath() {\n /* DEAD LOCK! */\n\nTracing should *never* block, as it can lead to strange lockups like the\nabove.\n\nRestructure the trace_clock_global() code to instead of simply taking a\nlock to update the recorded \"prev_time\" simply use it, as two events\nhappening on two different CPUs that calls this at the same time, really\ndoesn't matter which one goes first. Use a trylock to grab the lock for\nupdating the prev_time, and if it fails, simply try again the next time.\nIf it failed to be taken, that means something else is already updating\nit.\n\n\nBugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=212761"}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["kernel/trace/trace_clock.c"], "versions": [{"version": "14131f2f98ac350ee9e73faed916d2238a8b6a0d", "lessThan": "91ca6f6a91f679c8645d7f3307e03ce86ad518c4", "status": "affected", "versionType": "git"}, {"version": "14131f2f98ac350ee9e73faed916d2238a8b6a0d", "lessThan": "859b47a43f5a0e5b9a92b621dc6ceaad39fb5c8b", "status": "affected", "versionType": "git"}, {"version": "14131f2f98ac350ee9e73faed916d2238a8b6a0d", "lessThan": "1fca00920327be96f3318224f502e4d5460f9545", "status": "affected", "versionType": "git"}, {"version": "14131f2f98ac350ee9e73faed916d2238a8b6a0d", "lessThan": "d43d56dbf452ccecc1ec735cd4b6840118005d7c", "status": "affected", "versionType": "git"}, {"version": "14131f2f98ac350ee9e73faed916d2238a8b6a0d", "lessThan": "c64da3294a7d59a4bf6874c664c13be892f15f44", "status": "affected", "versionType": "git"}, {"version": "14131f2f98ac350ee9e73faed916d2238a8b6a0d", "lessThan": "a33614d52e97fc8077eb0b292189ca7d964cc534", "status": "affected", "versionType": "git"}, {"version": "14131f2f98ac350ee9e73faed916d2238a8b6a0d", "lessThan": "6e2418576228eeb12e7ba82edb8f9500623942ff", "status": "affected", "versionType": "git"}, {"version": "14131f2f98ac350ee9e73faed916d2238a8b6a0d", "lessThan": "2a1bd74b8186d7938bf004f5603f25b84785f63e", "status": "affected", "versionType": "git"}, {"version": "14131f2f98ac350ee9e73faed916d2238a8b6a0d", "lessThan": "aafe104aa9096827a429bc1358f8260ee565b7cc", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["kernel/trace/trace_clock.c"], "versions": [{"version": "2.6.30", "status": "affected"}, {"version": "0", "lessThan": "2.6.30", "status": "unaffected", "versionType": "semver"}, {"version": "4.4.269", "lessThanOrEqual": "4.4.*", "status": "unaffected", "versionType": "semver"}, {"version": "4.9.269", "lessThanOrEqual": "4.9.*", "status": "unaffected", "versionType": "semver"}, {"version": "4.14.233", "lessThanOrEqual": "4.14.*", "status": "unaffected", "versionType": "semver"}, {"version": "4.19.191", "lessThanOrEqual": "4.19.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.4.118", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.10.36", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.11.20", "lessThanOrEqual": "5.11.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.12.3", "lessThanOrEqual": "5.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.13", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.30", "versionEndExcluding": "4.4.269"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.30", "versionEndExcluding": "4.9.269"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.30", "versionEndExcluding": "4.14.233"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.30", "versionEndExcluding": "4.19.191"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": 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"https://git.kernel.org/stable/c/d43d56dbf452ccecc1ec735cd4b6840118005d7c"}, {"url": "https://git.kernel.org/stable/c/c64da3294a7d59a4bf6874c664c13be892f15f44"}, {"url": "https://git.kernel.org/stable/c/a33614d52e97fc8077eb0b292189ca7d964cc534"}, {"url": "https://git.kernel.org/stable/c/6e2418576228eeb12e7ba82edb8f9500623942ff"}, {"url": "https://git.kernel.org/stable/c/2a1bd74b8186d7938bf004f5603f25b84785f63e"}, {"url": "https://git.kernel.org/stable/c/aafe104aa9096827a429bc1358f8260ee565b7cc"}], "title": "tracing: Restructure trace_clock_global() to never block", "x_generator": {"engine": "bippy-1.2.0"}}, "adp": [{"problemTypes": [{"descriptions": [{"type": "CWE", "cweId": "CWE-400", "lang": "en", "description": "CWE-400 Uncontrolled Resource Consumption"}]}], "metrics": [{"cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.5, "attackVector": "LOCAL", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "NONE"}}, {"other": {"type": "ssvc", "content": {"timestamp": "2025-04-22T16:06:58.628047Z", "id": "CVE-2021-46939", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2025-04-22T16:08:05.513Z"}}, {"providerMetadata": {"orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2024-08-04T05:17:43.036Z"}, "title": "CVE Program Container", "references": [{"url": "https://git.kernel.org/stable/c/91ca6f6a91f679c8645d7f3307e03ce86ad518c4", "tags": ["x_transferred"]}, {"url": "https://git.kernel.org/stable/c/859b47a43f5a0e5b9a92b621dc6ceaad39fb5c8b", "tags": ["x_transferred"]}, {"url": 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{"url": "https://git.kernel.org/stable/c/aafe104aa9096827a429bc1358f8260ee565b7cc", "tags": ["x_transferred"]}], "providerMetadata": {"orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2024-08-04T05:17:43.036Z"}}, {"title": "CISA ADP Vulnrichment", "metrics": [{"cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.5, "attackVector": "LOCAL", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "NONE"}}, {"other": {"type": "ssvc", "content": {"id": "CVE-2021-46939", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2025-04-22T16:06:58.628047Z"}}}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-400", "description": "CWE-400 Uncontrolled Resource Consumption"}]}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2024-07-05T15:20:37.789Z"}}], "cna": {"title": "tracing: Restructure trace_clock_global() to never block", "affected": [{"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "14131f2f98ac350ee9e73faed916d2238a8b6a0d", "lessThan": "91ca6f6a91f679c8645d7f3307e03ce86ad518c4", "versionType": "git"}, {"status": "affected", "version": "14131f2f98ac350ee9e73faed916d2238a8b6a0d", "lessThan": "859b47a43f5a0e5b9a92b621dc6ceaad39fb5c8b", "versionType": "git"}, {"status": "affected", "version": "14131f2f98ac350ee9e73faed916d2238a8b6a0d", "lessThan": "1fca00920327be96f3318224f502e4d5460f9545", "versionType": "git"}, {"status": "affected", "version": "14131f2f98ac350ee9e73faed916d2238a8b6a0d", "lessThan": "d43d56dbf452ccecc1ec735cd4b6840118005d7c", "versionType": "git"}, {"status": "affected", "version": "14131f2f98ac350ee9e73faed916d2238a8b6a0d", "lessThan": "c64da3294a7d59a4bf6874c664c13be892f15f44", "versionType": "git"}, {"status": "affected", "version": "14131f2f98ac350ee9e73faed916d2238a8b6a0d", "lessThan": "a33614d52e97fc8077eb0b292189ca7d964cc534", "versionType": "git"}, {"status": "affected", "version": "14131f2f98ac350ee9e73faed916d2238a8b6a0d", "lessThan": "6e2418576228eeb12e7ba82edb8f9500623942ff", "versionType": "git"}, {"status": "affected", "version": "14131f2f98ac350ee9e73faed916d2238a8b6a0d", "lessThan": "2a1bd74b8186d7938bf004f5603f25b84785f63e", "versionType": "git"}, {"status": "affected", "version": "14131f2f98ac350ee9e73faed916d2238a8b6a0d", "lessThan": "aafe104aa9096827a429bc1358f8260ee565b7cc", "versionType": "git"}], "programFiles": ["kernel/trace/trace_clock.c"], "defaultStatus": "unaffected"}, {"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "2.6.30"}, {"status": "unaffected", "version": "0", "lessThan": "2.6.30", "versionType": "semver"}, {"status": "unaffected", "version": "4.4.269", "versionType": "semver", "lessThanOrEqual": "4.4.*"}, {"status": "unaffected", "version": "4.9.269", "versionType": "semver", "lessThanOrEqual": "4.9.*"}, {"status": "unaffected", "version": "4.14.233", "versionType": "semver", "lessThanOrEqual": "4.14.*"}, {"status": "unaffected", "version": "4.19.191", "versionType": "semver", "lessThanOrEqual": "4.19.*"}, {"status": "unaffected", "version": "5.4.118", "versionType": "semver", "lessThanOrEqual": "5.4.*"}, {"status": "unaffected", "version": "5.10.36", "versionType": "semver", "lessThanOrEqual": "5.10.*"}, {"status": "unaffected", "version": "5.11.20", "versionType": "semver", "lessThanOrEqual": "5.11.*"}, {"status": "unaffected", "version": "5.12.3", "versionType": "semver", "lessThanOrEqual": "5.12.*"}, {"status": "unaffected", "version": "5.13", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*"}], "programFiles": ["kernel/trace/trace_clock.c"], "defaultStatus": "affected"}], "references": [{"url": "https://git.kernel.org/stable/c/91ca6f6a91f679c8645d7f3307e03ce86ad518c4"}, {"url": "https://git.kernel.org/stable/c/859b47a43f5a0e5b9a92b621dc6ceaad39fb5c8b"}, {"url": "https://git.kernel.org/stable/c/1fca00920327be96f3318224f502e4d5460f9545"}, {"url": "https://git.kernel.org/stable/c/d43d56dbf452ccecc1ec735cd4b6840118005d7c"}, {"url": "https://git.kernel.org/stable/c/c64da3294a7d59a4bf6874c664c13be892f15f44"}, {"url": "https://git.kernel.org/stable/c/a33614d52e97fc8077eb0b292189ca7d964cc534"}, {"url": "https://git.kernel.org/stable/c/6e2418576228eeb12e7ba82edb8f9500623942ff"}, {"url": "https://git.kernel.org/stable/c/2a1bd74b8186d7938bf004f5603f25b84785f63e"}, {"url": "https://git.kernel.org/stable/c/aafe104aa9096827a429bc1358f8260ee565b7cc"}], "x_generator": {"engine": "bippy-1.2.0"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Restructure trace_clock_global() to never block\n\nIt was reported that a fix to the ring buffer recursion detection would\ncause a hung machine when performing suspend / resume testing. The\nfollowing backtrace was extracted from debugging that case:\n\nCall Trace:\n trace_clock_global+0x91/0xa0\n __rb_reserve_next+0x237/0x460\n ring_buffer_lock_reserve+0x12a/0x3f0\n trace_buffer_lock_reserve+0x10/0x50\n __trace_graph_return+0x1f/0x80\n trace_graph_return+0xb7/0xf0\n ? trace_clock_global+0x91/0xa0\n ftrace_return_to_handler+0x8b/0xf0\n ? pv_hash+0xa0/0xa0\n return_to_handler+0x15/0x30\n ? ftrace_graph_caller+0xa0/0xa0\n ? trace_clock_global+0x91/0xa0\n ? __rb_reserve_next+0x237/0x460\n ? ring_buffer_lock_reserve+0x12a/0x3f0\n ? trace_event_buffer_lock_reserve+0x3c/0x120\n ? trace_event_buffer_reserve+0x6b/0xc0\n ? trace_event_raw_event_device_pm_callback_start+0x125/0x2d0\n ? dpm_run_callback+0x3b/0xc0\n ? pm_ops_is_empty+0x50/0x50\n ? platform_get_irq_byname_optional+0x90/0x90\n ? trace_device_pm_callback_start+0x82/0xd0\n ? dpm_run_callback+0x49/0xc0\n\nWith the following RIP:\n\nRIP: 0010:native_queued_spin_lock_slowpath+0x69/0x200\n\nSince the fix to the recursion detection would allow a single recursion to\nhappen while tracing, this lead to the trace_clock_global() taking a spin\nlock and then trying to take it again:\n\nring_buffer_lock_reserve() {\n trace_clock_global() {\n arch_spin_lock() {\n queued_spin_lock_slowpath() {\n /* lock taken */\n (something else gets traced by function graph tracer)\n ring_buffer_lock_reserve() {\n trace_clock_global() {\n arch_spin_lock() {\n queued_spin_lock_slowpath() {\n /* DEAD LOCK! */\n\nTracing should *never* block, as it can lead to strange lockups like the\nabove.\n\nRestructure the trace_clock_global() code to instead of simply taking a\nlock to update the recorded \"prev_time\" simply use it, as two events\nhappening on two different CPUs that calls this at the same time, really\ndoesn't matter which one goes first. Use a trylock to grab the lock for\nupdating the prev_time, and if it fails, simply try again the next time.\nIf it failed to be taken, that means something else is already updating\nit.\n\n\nBugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=212761"}], "cpeApplicability": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "4.4.269", "versionStartIncluding": "2.6.30"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "4.9.269", "versionStartIncluding": "2.6.30"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "4.14.233", "versionStartIncluding": "2.6.30"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "4.19.191", "versionStartIncluding": "2.6.30"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.4.118", "versionStartIncluding": "2.6.30"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.10.36", "versionStartIncluding": "2.6.30"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.11.20", "versionStartIncluding": "2.6.30"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.12.3", "versionStartIncluding": "2.6.30"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.13", "versionStartIncluding": "2.6.30"}], "operator": "OR"}]}], "providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-05-11T13:44:49.866Z"}}}, "cveMetadata": {"cveId": "CVE-2021-46939", "state": "PUBLISHED", "dateUpdated": "2026-05-11T13:44:49.866Z", "dateReserved": "2024-02-25T13:45:52.721Z", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "datePublished": "2024-02-27T18:40:27.471Z", "assignerShortName": "Linux"}, "dataVersion": "5.2"}

{"configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "08CFB593-6583-4E68-8BFB-9326D7B17183", "versionEndExcluding": "4.4.269", "versionStartIncluding": "2.6.30", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "8413F613-F1EE-430D-9972-52EEF6C49672", "versionEndExcluding": "4.9.269", "versionStartIncluding": "4.5.0", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "20505383-2EB8-41EF-A91B-F185B4FB81DF", "versionEndExcluding": "4.14.233", "versionStartIncluding": "4.10.0", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "B7281E1E-A00B-49C0-A849-9CE1CE780227", "versionEndExcluding": "4.19.191", "versionStartIncluding": "4.15.0", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "5670AEA3-082C-42D6-A067-CD9ECED4B84B", "versionEndExcluding": "5.4.118", "versionStartIncluding": "4.20.0", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "C7148769-B830-4B8F-986F-E0C85A19FC7F", "versionEndExcluding": "5.10.36", "versionStartIncluding": "5.5.0", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "EFB425F0-C28C-4B44-8B4C-AD512AA832DE", "versionEndExcluding": "5.11.20", "versionStartIncluding": "5.11.0", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "C3814FA3-8141-4313-A852-8C4212BE12AD", "versionEndExcluding": "5.12.3", "versionStartIncluding": "5.12.0", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Restructure trace_clock_global() to never block\n\nIt was reported that a fix to the ring buffer recursion detection would\ncause a hung machine when performing suspend / resume testing. The\nfollowing backtrace was extracted from debugging that case:\n\nCall Trace:\n trace_clock_global+0x91/0xa0\n __rb_reserve_next+0x237/0x460\n ring_buffer_lock_reserve+0x12a/0x3f0\n trace_buffer_lock_reserve+0x10/0x50\n __trace_graph_return+0x1f/0x80\n trace_graph_return+0xb7/0xf0\n ? trace_clock_global+0x91/0xa0\n ftrace_return_to_handler+0x8b/0xf0\n ? pv_hash+0xa0/0xa0\n return_to_handler+0x15/0x30\n ? ftrace_graph_caller+0xa0/0xa0\n ? trace_clock_global+0x91/0xa0\n ? __rb_reserve_next+0x237/0x460\n ? ring_buffer_lock_reserve+0x12a/0x3f0\n ? trace_event_buffer_lock_reserve+0x3c/0x120\n ? trace_event_buffer_reserve+0x6b/0xc0\n ? trace_event_raw_event_device_pm_callback_start+0x125/0x2d0\n ? dpm_run_callback+0x3b/0xc0\n ? pm_ops_is_empty+0x50/0x50\n ? platform_get_irq_byname_optional+0x90/0x90\n ? trace_device_pm_callback_start+0x82/0xd0\n ? dpm_run_callback+0x49/0xc0\n\nWith the following RIP:\n\nRIP: 0010:native_queued_spin_lock_slowpath+0x69/0x200\n\nSince the fix to the recursion detection would allow a single recursion to\nhappen while tracing, this lead to the trace_clock_global() taking a spin\nlock and then trying to take it again:\n\nring_buffer_lock_reserve() {\n trace_clock_global() {\n arch_spin_lock() {\n queued_spin_lock_slowpath() {\n /* lock taken */\n (something else gets traced by function graph tracer)\n ring_buffer_lock_reserve() {\n trace_clock_global() {\n arch_spin_lock() {\n queued_spin_lock_slowpath() {\n /* DEAD LOCK! */\n\nTracing should *never* block, as it can lead to strange lockups like the\nabove.\n\nRestructure the trace_clock_global() code to instead of simply taking a\nlock to update the recorded \"prev_time\" simply use it, as two events\nhappening on two different CPUs that calls this at the same time, really\ndoesn't matter which one goes first. Use a trylock to grab the lock for\nupdating the prev_time, and if it fails, simply try again the next time.\nIf it failed to be taken, that means something else is already updating\nit.\n\n\nBugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=212761"}, {"lang": "es", "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: rastreo: reestructurar trace_clock_global() para no bloquear nunca. Se inform\u00f3 que una soluci\u00f3n a la detecci\u00f3n de recursividad del b\u00fafer circular provocar\u00eda que la m\u00e1quina se bloqueara al realizar pruebas de suspensi\u00f3n/reanudaci\u00f3n. El siguiente seguimiento se extrajo de la depuraci\u00f3n de ese caso: Call Trace: trace_clock_global+0x91/0xa0 __rb_reserve_next+0x237/0x460 ring_buffer_lock_reserve+0x12a/0x3f0 trace_buffer_lock_reserve+0x10/0x50 __trace_graph_return+0x1f/0x80 trace_graph_return+0xb7 /0xf0? trace_clock_global+0x91/0xa0 ftrace_return_to_handler+0x8b/0xf0 ? pv_hash+0xa0/0xa0 return_to_handler+0x15/0x30 ? ftrace_graph_caller+0xa0/0xa0? trace_clock_global+0x91/0xa0? __rb_reserve_next+0x237/0x460? ring_buffer_lock_reserve+0x12a/0x3f0? trace_event_buffer_lock_reserve+0x3c/0x120? trace_event_buffer_reserve+0x6b/0xc0? trace_event_raw_event_device_pm_callback_start+0x125/0x2d0? dpm_run_callback+0x3b/0xc0? pm_ops_is_empty+0x50/0x50? platform_get_irq_byname_opcional+0x90/0x90? trace_device_pm_callback_start+0x82/0xd0? dpm_run_callback+0x49/0xc0 Con el siguiente RIP: RIP: 0010:native_queued_spin_lock_slowpath+0x69/0x200 Dado que la soluci\u00f3n a la detecci\u00f3n de recursi\u00f3n permitir\u00eda que ocurriera una sola recursi\u00f3n durante el seguimiento, esto llev\u00f3 a trace_clock_global() a tomar un bloqueo de giro y luego intentarlo para tomarlo de nuevo: ring_buffer_lock_reserve() { trace_clock_global() { arch_spin_lock() { queued_spin_lock_slowpath() { /* bloqueo tomado */ (algo m\u00e1s es rastreado por la funci\u00f3n de seguimiento del gr\u00e1fico) ring_buffer_lock_reserve() { trace_clock_global() { arch_spin_lock() { queued_spin_lock_slowpath () { /* \u00a1BLOQUEO MUERTO! */ El rastreo *nunca* debe bloquearse, ya que puede provocar bloqueos extra\u00f1os como el anterior. Reestructura el c\u00f3digo trace_clock_global() para que, en lugar de simplemente tomar un bloqueo para actualizar el \"prev_time\" registrado, simplemente lo uses, ya que dos eventos suceden en dos CPU diferentes que llaman a esto al mismo tiempo, realmente no importa cu\u00e1l va primero. Utilice un trylock para obtener el bloqueo para actualizar prev_time y, si falla, simplemente int\u00e9ntelo de nuevo la pr\u00f3xima vez. Si no se pudo tomar, eso significa que algo m\u00e1s ya lo est\u00e1 actualizando. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=212761"}], "id": "CVE-2021-46939", "lastModified": "2025-04-22T16:15:19.423", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 5.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 3.6, "source": "nvd@nist.gov", "type": "Primary"}, {"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 5.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 3.6, "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}, "published": "2024-02-27T19:04:05.873", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/1fca00920327be96f3318224f502e4d5460f9545"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/2a1bd74b8186d7938bf004f5603f25b84785f63e"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/6e2418576228eeb12e7ba82edb8f9500623942ff"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/859b47a43f5a0e5b9a92b621dc6ceaad39fb5c8b"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/91ca6f6a91f679c8645d7f3307e03ce86ad518c4"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/a33614d52e97fc8077eb0b292189ca7d964cc534"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/aafe104aa9096827a429bc1358f8260ee565b7cc"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/c64da3294a7d59a4bf6874c664c13be892f15f44"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/d43d56dbf452ccecc1ec735cd4b6840118005d7c"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/1fca00920327be96f3318224f502e4d5460f9545"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/2a1bd74b8186d7938bf004f5603f25b84785f63e"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/6e2418576228eeb12e7ba82edb8f9500623942ff"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/859b47a43f5a0e5b9a92b621dc6ceaad39fb5c8b"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/91ca6f6a91f679c8645d7f3307e03ce86ad518c4"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/a33614d52e97fc8077eb0b292189ca7d964cc534"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/aafe104aa9096827a429bc1358f8260ee565b7cc"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/c64da3294a7d59a4bf6874c664c13be892f15f44"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/d43d56dbf452ccecc1ec735cd4b6840118005d7c"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Modified", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-662"}], "source": "nvd@nist.gov", "type": "Primary"}, {"description": [{"lang": "en", "value": "CWE-400"}], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}

{"affected_release": [{"advisory": "RHSA-2024:5102", "cpe": "cpe:/a:redhat:enterprise_linux:8::nfv", "package": "kernel-rt-0:4.18.0-553.16.1.rt7.357.el8_10", "product_name": "Red Hat Enterprise Linux 8", "release_date": "2024-08-08T00:00:00Z"}, {"advisory": "RHSA-2024:5101", "cpe": "cpe:/o:redhat:enterprise_linux:8", "package": "kernel-0:4.18.0-553.16.1.el8_10", "product_name": "Red Hat Enterprise Linux 8", "release_date": "2024-08-08T00:00:00Z"}], "bugzilla": {"description": "kernel: tracing: Restructure trace_clock_global() to never block", "id": "2266497", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2266497"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "verified"}, "cwe": "CWE-833", "details": ["In the Linux kernel, the following vulnerability has been resolved:\ntracing: Restructure trace_clock_global() to never block\nIt was reported that a fix to the ring buffer recursion detection would\ncause a hung machine when performing suspend / resume testing. The\nfollowing backtrace was extracted from debugging that case:\nCall Trace:\ntrace_clock_global+0x91/0xa0\n__rb_reserve_next+0x237/0x460\nring_buffer_lock_reserve+0x12a/0x3f0\ntrace_buffer_lock_reserve+0x10/0x50\n__trace_graph_return+0x1f/0x80\ntrace_graph_return+0xb7/0xf0\n? trace_clock_global+0x91/0xa0\nftrace_return_to_handler+0x8b/0xf0\n? pv_hash+0xa0/0xa0\nreturn_to_handler+0x15/0x30\n? ftrace_graph_caller+0xa0/0xa0\n? trace_clock_global+0x91/0xa0\n? __rb_reserve_next+0x237/0x460\n? ring_buffer_lock_reserve+0x12a/0x3f0\n? trace_event_buffer_lock_reserve+0x3c/0x120\n? trace_event_buffer_reserve+0x6b/0xc0\n? trace_event_raw_event_device_pm_callback_start+0x125/0x2d0\n? dpm_run_callback+0x3b/0xc0\n? pm_ops_is_empty+0x50/0x50\n? platform_get_irq_byname_optional+0x90/0x90\n? trace_device_pm_callback_start+0x82/0xd0\n? dpm_run_callback+0x49/0xc0\nWith the following RIP:\nRIP: 0010:native_queued_spin_lock_slowpath+0x69/0x200\nSince the fix to the recursion detection would allow a single recursion to\nhappen while tracing, this lead to the trace_clock_global() taking a spin\nlock and then trying to take it again:\nring_buffer_lock_reserve() {\ntrace_clock_global() {\narch_spin_lock() {\nqueued_spin_lock_slowpath() {\n/* lock taken */\n(something else gets traced by function graph tracer)\nring_buffer_lock_reserve() {\ntrace_clock_global() {\narch_spin_lock() {\nqueued_spin_lock_slowpath() {\n/* DEAD LOCK! */\nTracing should *never* block, as it can lead to strange lockups like the\nabove.\nRestructure the trace_clock_global() code to instead of simply taking a\nlock to update the recorded \"prev_time\" simply use it, as two events\nhappening on two different CPUs that calls this at the same time, really\ndoesn't matter which one goes first. Use a trylock to grab the lock for\nupdating the prev_time, and if it fails, simply try again the next time.\nIf it failed to be taken, that means something else is already updating\nit.\nBugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=212761"], "name": "CVE-2021-46939", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2024-02-27T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2021-46939\nhttps://nvd.nist.gov/vuln/detail/CVE-2021-46939\nhttps://lore.kernel.org/linux-cve-announce/20240227184057.2368370-4-gregkh@linuxfoundation.org/T/#u"], "threat_severity": "Moderate"}

{}