7.8

CVE-2024-44941

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

f2fs: fix to cover read extent cache access with lock

syzbot reports a f2fs bug as below:

BUG: KASAN: slab-use-after-free in sanity_check_extent_cache+0x370/0x410 fs/f2fs/extent_cache.c:46
Read of size 4 at addr ffff8880739ab220 by task syz-executor200/5097

CPU: 0 PID: 5097 Comm: syz-executor200 Not tainted 6.9.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 sanity_check_extent_cache+0x370/0x410 fs/f2fs/extent_cache.c:46
 do_read_inode fs/f2fs/inode.c:509 [inline]
 f2fs_iget+0x33e1/0x46e0 fs/f2fs/inode.c:560
 f2fs_nfs_get_inode+0x74/0x100 fs/f2fs/super.c:3237
 generic_fh_to_dentry+0x9f/0xf0 fs/libfs.c:1413
 exportfs_decode_fh_raw+0x152/0x5f0 fs/exportfs/expfs.c:444
 exportfs_decode_fh+0x3c/0x80 fs/exportfs/expfs.c:584
 do_handle_to_path fs/fhandle.c:155 [inline]
 handle_to_path fs/fhandle.c:210 [inline]
 do_handle_open+0x495/0x650 fs/fhandle.c:226
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

We missed to cover sanity_check_extent_cache() w/ extent cache lock,
so, below race case may happen, result in use after free issue.

- f2fs_iget
 - do_read_inode
  - f2fs_init_read_extent_tree
  : add largest extent entry in to cache
					- shrink
					 - f2fs_shrink_read_extent_tree
					  - __shrink_extent_tree
					   - __detach_extent_node
					   : drop largest extent entry
  - sanity_check_extent_cache
  : access et->largest w/o lock

let's refactor sanity_check_extent_cache() to avoid extent cache access
and call it before f2fs_init_read_extent_tree() to fix this issue.
Daten sind bereitgestellt durch National Vulnerability Database (NVD)
Linux ≫ Linux Kernel Version < 6.6.47
Linux ≫ Linux Kernel Version >= 6.7 < 6.10.6
Zu dieser CVE wurde keine CISA KEV oder CERT.AT-Warnung gefunden.
EPSS Metriken
Typ Quelle Score Percentile
EPSS FIRST.org 0.03% 0.08
CVSS Metriken
Quelle Base Score Exploit Score Impact Score Vector String
nvd@nist.gov 7.8 1.8 5.9
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE-416 Use After Free

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.