Description
In the Linux kernel, the following vulnerability has been resolved:

drm/i915/ttm: fix CCS handling

Crucible + recent Mesa seems to sometimes hit:

GEM_BUG_ON(num_ccs_blks > NUM_CCS_BLKS_PER_XFER)

And it looks like we can also trigger this with gem_lmem_swapping, if we
modify the test to use slightly larger object sizes.

Looking closer it looks like we have the following issues in
migrate_copy():

- We are using plain integer in various places, which we can easily
overflow with a large object.

- We pass the entire object size (when the src is lmem) into
emit_pte() and then try to copy it, which doesn't work, since we
only have a few fixed sized windows in which to map the pages and
perform the copy. With an object > 8M we therefore aren't properly
copying the pages. And then with an object > 64M we trigger the
GEM_BUG_ON(num_ccs_blks > NUM_CCS_BLKS_PER_XFER).

So it looks like our copy handling for any object > 8M (which is our
CHUNK_SZ) is currently broken on DG2.

Testcase: igt@gem_lmem_swapping
(cherry picked from commit 8676145eb2f53a9940ff70910caf0125bd8a4bc2)
Published: 2025-06-18
Score: 5.5 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
EUVD EUVD EUVD-2022-55245 In the Linux kernel, the following vulnerability has been resolved: drm/i915/ttm: fix CCS handling Crucible + recent Mesa seems to sometimes hit: GEM_BUG_ON(num_ccs_blks > NUM_CCS_BLKS_PER_XFER) And it looks like we can also trigger this with gem_lmem_swapping, if we modify the test to use slightly larger object sizes. Looking closer it looks like we have the following issues in migrate_copy(): - We are using plain integer in various places, which we can easily overflow with a large object. - We pass the entire object size (when the src is lmem) into emit_pte() and then try to copy it, which doesn't work, since we only have a few fixed sized windows in which to map the pages and perform the copy. With an object > 8M we therefore aren't properly copying the pages. And then with an object > 64M we trigger the GEM_BUG_ON(num_ccs_blks > NUM_CCS_BLKS_PER_XFER). So it looks like our copy handling for any object > 8M (which is our CHUNK_SZ) is currently broken on DG2. Testcase: igt@gem_lmem_swapping (cherry picked from commit 8676145eb2f53a9940ff70910caf0125bd8a4bc2)
History

Fri, 14 Nov 2025 18:15:00 +0000

Type Values Removed Values Added
Weaknesses NVD-CWE-noinfo
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.0:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.0:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.0:rc3:*:*:*:*:*:*

Fri, 20 Jun 2025 14:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate


Wed, 18 Jun 2025 11:15:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: drm/i915/ttm: fix CCS handling Crucible + recent Mesa seems to sometimes hit: GEM_BUG_ON(num_ccs_blks > NUM_CCS_BLKS_PER_XFER) And it looks like we can also trigger this with gem_lmem_swapping, if we modify the test to use slightly larger object sizes. Looking closer it looks like we have the following issues in migrate_copy(): - We are using plain integer in various places, which we can easily overflow with a large object. - We pass the entire object size (when the src is lmem) into emit_pte() and then try to copy it, which doesn't work, since we only have a few fixed sized windows in which to map the pages and perform the copy. With an object > 8M we therefore aren't properly copying the pages. And then with an object > 64M we trigger the GEM_BUG_ON(num_ccs_blks > NUM_CCS_BLKS_PER_XFER). So it looks like our copy handling for any object > 8M (which is our CHUNK_SZ) is currently broken on DG2. Testcase: igt@gem_lmem_swapping (cherry picked from commit 8676145eb2f53a9940ff70910caf0125bd8a4bc2)
Title drm/i915/ttm: fix CCS handling
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-05-11T19:10:05.264Z

Reserved: 2025-06-18T10:57:27.384Z

Link: CVE-2022-49963

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Analyzed

Published: 2025-06-18T11:15:23.570

Modified: 2025-11-14T18:08:38.360

Link: CVE-2022-49963

cve-icon Redhat

Severity : Moderate

Publid Date: 2025-06-18T00:00:00Z

Links: CVE-2022-49963 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2025-06-23T08:45:30Z

Weaknesses