7.8

CVE-2025-21631

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

block, bfq: fix waker_bfqq UAF after bfq_split_bfqq()

Our syzkaller report a following UAF for v6.6:

BUG: KASAN: slab-use-after-free in bfq_init_rq+0x175d/0x17a0 block/bfq-iosched.c:6958
Read of size 8 at addr ffff8881b57147d8 by task fsstress/232726

CPU: 2 PID: 232726 Comm: fsstress Not tainted 6.6.0-g3629d1885222 #39
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x91/0xf0 lib/dump_stack.c:106
 print_address_description.constprop.0+0x66/0x300 mm/kasan/report.c:364
 print_report+0x3e/0x70 mm/kasan/report.c:475
 kasan_report+0xb8/0xf0 mm/kasan/report.c:588
 hlist_add_head include/linux/list.h:1023 [inline]
 bfq_init_rq+0x175d/0x17a0 block/bfq-iosched.c:6958
 bfq_insert_request.isra.0+0xe8/0xa20 block/bfq-iosched.c:6271
 bfq_insert_requests+0x27f/0x390 block/bfq-iosched.c:6323
 blk_mq_insert_request+0x290/0x8f0 block/blk-mq.c:2660
 blk_mq_submit_bio+0x1021/0x15e0 block/blk-mq.c:3143
 __submit_bio+0xa0/0x6b0 block/blk-core.c:639
 __submit_bio_noacct_mq block/blk-core.c:718 [inline]
 submit_bio_noacct_nocheck+0x5b7/0x810 block/blk-core.c:747
 submit_bio_noacct+0xca0/0x1990 block/blk-core.c:847
 __ext4_read_bh fs/ext4/super.c:205 [inline]
 ext4_read_bh+0x15e/0x2e0 fs/ext4/super.c:230
 __read_extent_tree_block+0x304/0x6f0 fs/ext4/extents.c:567
 ext4_find_extent+0x479/0xd20 fs/ext4/extents.c:947
 ext4_ext_map_blocks+0x1a3/0x2680 fs/ext4/extents.c:4182
 ext4_map_blocks+0x929/0x15a0 fs/ext4/inode.c:660
 ext4_iomap_begin_report+0x298/0x480 fs/ext4/inode.c:3569
 iomap_iter+0x3dd/0x1010 fs/iomap/iter.c:91
 iomap_fiemap+0x1f4/0x360 fs/iomap/fiemap.c:80
 ext4_fiemap+0x181/0x210 fs/ext4/extents.c:5051
 ioctl_fiemap.isra.0+0x1b4/0x290 fs/ioctl.c:220
 do_vfs_ioctl+0x31c/0x11a0 fs/ioctl.c:811
 __do_sys_ioctl fs/ioctl.c:869 [inline]
 __se_sys_ioctl+0xae/0x190 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x70/0x120 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x78/0xe2

Allocated by task 232719:
 kasan_save_stack+0x22/0x50 mm/kasan/common.c:45
 kasan_set_track+0x25/0x30 mm/kasan/common.c:52
 __kasan_slab_alloc+0x87/0x90 mm/kasan/common.c:328
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook mm/slab.h:768 [inline]
 slab_alloc_node mm/slub.c:3492 [inline]
 kmem_cache_alloc_node+0x1b8/0x6f0 mm/slub.c:3537
 bfq_get_queue+0x215/0x1f00 block/bfq-iosched.c:5869
 bfq_get_bfqq_handle_split+0x167/0x5f0 block/bfq-iosched.c:6776
 bfq_init_rq+0x13a4/0x17a0 block/bfq-iosched.c:6938
 bfq_insert_request.isra.0+0xe8/0xa20 block/bfq-iosched.c:6271
 bfq_insert_requests+0x27f/0x390 block/bfq-iosched.c:6323
 blk_mq_insert_request+0x290/0x8f0 block/blk-mq.c:2660
 blk_mq_submit_bio+0x1021/0x15e0 block/blk-mq.c:3143
 __submit_bio+0xa0/0x6b0 block/blk-core.c:639
 __submit_bio_noacct_mq block/blk-core.c:718 [inline]
 submit_bio_noacct_nocheck+0x5b7/0x810 block/blk-core.c:747
 submit_bio_noacct+0xca0/0x1990 block/blk-core.c:847
 __ext4_read_bh fs/ext4/super.c:205 [inline]
 ext4_read_bh_nowait+0x15a/0x240 fs/ext4/super.c:217
 ext4_read_bh_lock+0xac/0xd0 fs/ext4/super.c:242
 ext4_bread_batch+0x268/0x500 fs/ext4/inode.c:958
 __ext4_find_entry+0x448/0x10f0 fs/ext4/namei.c:1671
 ext4_lookup_entry fs/ext4/namei.c:1774 [inline]
 ext4_lookup.part.0+0x359/0x6f0 fs/ext4/namei.c:1842
 ext4_lookup+0x72/0x90 fs/ext4/namei.c:1839
 __lookup_slow+0x257/0x480 fs/namei.c:1696
 lookup_slow fs/namei.c:1713 [inline]
 walk_component+0x454/0x5c0 fs/namei.c:2004
 link_path_walk.part.0+0x773/0xda0 fs/namei.c:2331
 link_path_walk fs/namei.c:3826 [inline]
 path_openat+0x1b9/0x520 fs/namei.c:3826
 do_filp_open+0x1b7/0x400 fs/namei.c:3857
 do_sys_openat2+0x5dc/0x6e0 fs/open.c:1428
 do_sys_open fs/open.c:1443 [inline]
 __do_sys_openat fs/open.c:1459 [inline]
 __se_sys_openat fs/open.c:1454 [inline]
 __x64_sys_openat+0x148/0x200 fs/open.c:1454
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_6
---truncated---
Data is provided by the National Vulnerability Database (NVD)
Linux ≫ Linux Kernel Version >= 5.15.168 < 5.15.177
Linux ≫ Linux Kernel Version >= 6.1.113 < 6.1.125
Linux ≫ Linux Kernel Version >= 6.6.54 < 6.6.72
Linux ≫ Linux Kernel Version >= 6.10.13 < 6.11
Linux ≫ Linux Kernel Version >= 6.11.2 < 6.12.10
Linux ≫ Linux Kernel Version6.13 Updaterc1
Linux ≫ Linux Kernel Version6.13 Updaterc2
Linux ≫ Linux Kernel Version6.13 Updaterc3
Linux ≫ Linux Kernel Version6.13 Updaterc4
Linux ≫ Linux Kernel Version6.13 Updaterc5
Linux ≫ Linux Kernel Version6.13 Updaterc6
Zu dieser CVE wurde keine CISA KEV oder CERT.AT-Warnung gefunden.
EPSS Metriken
Type Source Score Percentile
EPSS FIRST.org 0.04% 0.1
CVSS Metriken
Source 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
134c704f-9b21-4f2e-91b3-4a467353bcc0 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.