btrfs: send: fix buffer overflow detection when copying path to cache entry
Starting with commit c0247d289e73 ("btrfs: send: annotate struct
name_cache_entry with __counted_by()") we annotated the variable length
array "name" from the name_cache_entry structure with __counted_by() to
improve overflow detection. However that alone was not correct, because
the length of that array does not match the "name_len" field - it matches
that plus 1 to include the NUL string terminator, so that makes a
fortified kernel think there's an overflow and report a splat like this:
strcpy: detected buffer overflow: 20 byte write of buffer size 19
WARNING: CPU: 3 PID: 3310 at __fortify_report+0x45/0x50
CPU: 3 UID: 0 PID: 3310 Comm: btrfs Not tainted 6.11.0-prnet #1
Hardware name: CompuLab Ltd. sbc-ihsw/Intense-PC2 (IPC2), BIOS IPC2_3.330.7 X64 03/15/2018
RIP: 0010:__fortify_report+0x45/0x50
Code: 48 8b 34 (...)
RSP: 0018:ffff97ebc0d6f650 EFLAGS: 00010246
RAX: 7749924ef60fa600 RBX: ffff8bf5446a521a RCX: 0000000000000027
RDX: 00000000ffffdfff RSI: ffff97ebc0d6f548 RDI: ffff8bf84e7a1cc8
RBP: ffff8bf548574080 R08: ffffffffa8c40e10 R09: 0000000000005ffd
R10: 0000000000000004 R11: ffffffffa8c70e10 R12: ffff8bf551eef400
R13: 0000000000000000 R14: 0000000000000013 R15: 00000000000003a8
FS: 00007fae144de8c0(0000) GS:ffff8bf84e780000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fae14691690 CR3: 00000001027a2003 CR4: 00000000001706f0
Call Trace:
<TASK>
? __warn+0x12a/0x1d0
? __fortify_report+0x45/0x50
? report_bug+0x154/0x1c0
? handle_bug+0x42/0x70
? exc_invalid_op+0x1a/0x50
? asm_exc_invalid_op+0x1a/0x20
? __fortify_report+0x45/0x50
__fortify_panic+0x9/0x10
__get_cur_name_and_parent+0x3bc/0x3c0
get_cur_path+0x207/0x3b0
send_extent_data+0x709/0x10d0
? find_parent_nodes+0x22df/0x25d0
? mas_nomem+0x13/0x90
? mtree_insert_range+0xa5/0x110
? btrfs_lru_cache_store+0x5f/0x1e0
? iterate_extent_inodes+0x52d/0x5a0
process_extent+0xa96/0x11a0
? __pfx_lookup_backref_cache+0x10/0x10
? __pfx_store_backref_cache+0x10/0x10
? __pfx_iterate_backrefs+0x10/0x10
? __pfx_check_extent_item+0x10/0x10
changed_cb+0x6fa/0x930
? tree_advance+0x362/0x390
? memcmp_extent_buffer+0xd7/0x160
send_subvol+0xf0a/0x1520
btrfs_ioctl_send+0x106b/0x11d0
? __pfx___clone_root_cmp_sort+0x10/0x10
_btrfs_ioctl_send+0x1ac/0x240
btrfs_ioctl+0x75b/0x850
__se_sys_ioctl+0xca/0x150
do_syscall_64+0x85/0x160
? __count_memcg_events+0x69/0x100
? handle_mm_fault+0x1327/0x15c0
? __se_sys_rt_sigprocmask+0xf1/0x180
? syscall_exit_to_user_mode+0x75/0xa0
? do_syscall_64+0x91/0x160
? do_user_addr_fault+0x21d/0x630
entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7fae145eeb4f
Code: 00 48 89 (...)
RSP: 002b:00007ffdf1cb09b0 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007fae145eeb4f
RDX: 00007ffdf1cb0ad0 RSI: 0000000040489426 RDI: 0000000000000004
RBP: 00000000000078fe R08: 00007fae144006c0 R09: 00007ffdf1cb0927
R10: 0000000000000008 R11: 0000000000000246 R12: 00007ffdf1cb1ce8
R13: 0000000000000003 R14: 000055c499fab2e0 R15: 0000000000000004
</TASK>
Fix this by not storing the NUL string terminator since we don't actually
need it for name cache entries, this way "name_len" corresponds to the
actual size of the "name" array. This requires marking the "name" array
field with __nonstring and using memcpy() instead of strcpy() as
recommended by the guidelines at:
https://github.com/KSPP/linux/issues/90
Analysis and contextual insights are available on OpenCVE Cloud.
No vendor fix or workaround currently provided.
Additional remediation guidance may be available on OpenCVE Cloud.
Tracking
Sign in to view the affected projects.
| Source | ID | Title |
|---|---|---|
Ubuntu USN |
USN-7276-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7277-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7310-1 | Linux kernel vulnerabilities |
Thu, 24 Oct 2024 20:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Linux
Linux linux Kernel |
|
| Weaknesses | CWE-120 | |
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| Metrics |
cvssV3_1
|
cvssV3_1
|
Wed, 23 Oct 2024 01:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
| |
| Metrics |
threat_severity
|
cvssV3_1
|
Tue, 22 Oct 2024 14:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
Mon, 21 Oct 2024 18:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: btrfs: send: fix buffer overflow detection when copying path to cache entry Starting with commit c0247d289e73 ("btrfs: send: annotate struct name_cache_entry with __counted_by()") we annotated the variable length array "name" from the name_cache_entry structure with __counted_by() to improve overflow detection. However that alone was not correct, because the length of that array does not match the "name_len" field - it matches that plus 1 to include the NUL string terminator, so that makes a fortified kernel think there's an overflow and report a splat like this: strcpy: detected buffer overflow: 20 byte write of buffer size 19 WARNING: CPU: 3 PID: 3310 at __fortify_report+0x45/0x50 CPU: 3 UID: 0 PID: 3310 Comm: btrfs Not tainted 6.11.0-prnet #1 Hardware name: CompuLab Ltd. sbc-ihsw/Intense-PC2 (IPC2), BIOS IPC2_3.330.7 X64 03/15/2018 RIP: 0010:__fortify_report+0x45/0x50 Code: 48 8b 34 (...) RSP: 0018:ffff97ebc0d6f650 EFLAGS: 00010246 RAX: 7749924ef60fa600 RBX: ffff8bf5446a521a RCX: 0000000000000027 RDX: 00000000ffffdfff RSI: ffff97ebc0d6f548 RDI: ffff8bf84e7a1cc8 RBP: ffff8bf548574080 R08: ffffffffa8c40e10 R09: 0000000000005ffd R10: 0000000000000004 R11: ffffffffa8c70e10 R12: ffff8bf551eef400 R13: 0000000000000000 R14: 0000000000000013 R15: 00000000000003a8 FS: 00007fae144de8c0(0000) GS:ffff8bf84e780000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fae14691690 CR3: 00000001027a2003 CR4: 00000000001706f0 Call Trace: <TASK> ? __warn+0x12a/0x1d0 ? __fortify_report+0x45/0x50 ? report_bug+0x154/0x1c0 ? handle_bug+0x42/0x70 ? exc_invalid_op+0x1a/0x50 ? asm_exc_invalid_op+0x1a/0x20 ? __fortify_report+0x45/0x50 __fortify_panic+0x9/0x10 __get_cur_name_and_parent+0x3bc/0x3c0 get_cur_path+0x207/0x3b0 send_extent_data+0x709/0x10d0 ? find_parent_nodes+0x22df/0x25d0 ? mas_nomem+0x13/0x90 ? mtree_insert_range+0xa5/0x110 ? btrfs_lru_cache_store+0x5f/0x1e0 ? iterate_extent_inodes+0x52d/0x5a0 process_extent+0xa96/0x11a0 ? __pfx_lookup_backref_cache+0x10/0x10 ? __pfx_store_backref_cache+0x10/0x10 ? __pfx_iterate_backrefs+0x10/0x10 ? __pfx_check_extent_item+0x10/0x10 changed_cb+0x6fa/0x930 ? tree_advance+0x362/0x390 ? memcmp_extent_buffer+0xd7/0x160 send_subvol+0xf0a/0x1520 btrfs_ioctl_send+0x106b/0x11d0 ? __pfx___clone_root_cmp_sort+0x10/0x10 _btrfs_ioctl_send+0x1ac/0x240 btrfs_ioctl+0x75b/0x850 __se_sys_ioctl+0xca/0x150 do_syscall_64+0x85/0x160 ? __count_memcg_events+0x69/0x100 ? handle_mm_fault+0x1327/0x15c0 ? __se_sys_rt_sigprocmask+0xf1/0x180 ? syscall_exit_to_user_mode+0x75/0xa0 ? do_syscall_64+0x91/0x160 ? do_user_addr_fault+0x21d/0x630 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7fae145eeb4f Code: 00 48 89 (...) RSP: 002b:00007ffdf1cb09b0 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007fae145eeb4f RDX: 00007ffdf1cb0ad0 RSI: 0000000040489426 RDI: 0000000000000004 RBP: 00000000000078fe R08: 00007fae144006c0 R09: 00007ffdf1cb0927 R10: 0000000000000008 R11: 0000000000000246 R12: 00007ffdf1cb1ce8 R13: 0000000000000003 R14: 000055c499fab2e0 R15: 0000000000000004 </TASK> Fix this by not storing the NUL string terminator since we don't actually need it for name cache entries, this way "name_len" corresponds to the actual size of the "name" array. This requires marking the "name" array field with __nonstring and using memcpy() instead of strcpy() as recommended by the guidelines at: https://github.com/KSPP/linux/issues/90 | |
| Title | btrfs: send: fix buffer overflow detection when copying path to cache entry | |
| References |
|
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-05-11T20:40:48.614Z
Reserved: 2024-10-21T12:17:06.019Z
Link: CVE-2024-49869
Updated: 2024-10-22T13:47:15.316Z
Status : Analyzed
Published: 2024-10-21T18:15:08.340
Modified: 2024-10-24T20:28:21.597
Link: CVE-2024-49869
OpenCVE Enrichment
No data.
Ubuntu USN