KASAN: use-after-free Read in udf_free_inode (3)

Status: upstream: reported on 2026/08/16 19:06
Reported-by: syzbot+f6a0222802ce732a6f6e@syzkaller.appspotmail.com
First crash: 2d00h, last: 2d00h
Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: use-after-free Read in udf_free_inode fs 19 1 1330d 1326d 0/29 auto-obsoleted due to no activity on 2023/03/26 23:00
linux-6.1 BUG: unable to handle kernel paging request in udf_free_inode (2) origin:upstream missing-backport 19 syz, C error 26 101d 336d 0/3 upstream: reported C repro on 2025/09/16 08:14
linux-5.15 KASAN: use-after-free Read in udf_free_inode (2) 19 4 235d 335d 0/3 auto-obsoleted due to no activity on 2026/04/05 15:40
linux-5.15 KASAN: use-after-free Read in udf_free_inode 19 1 583d 583d 0/3 auto-obsoleted due to no activity on 2025/04/22 09:43
linux-6.1 KASAN: use-after-free Read in udf_free_inode 19 1 778d 778d 0/3 auto-obsoleted due to no activity on 2024/10/09 09:17
upstream BUG: unable to handle kernel paging request in udf_free_inode udf 8 1 1756d 1752d 0/29 auto-closed as invalid on 2022/01/25 11:13
linux-6.1 BUG: unable to handle kernel paging request in udf_free_inode 8 1 650d 650d 0/3 auto-obsoleted due to no activity on 2025/02/14 07:32

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in le32_add_cpu include/linux/byteorder/generic.h:151 [inline]
BUG: KASAN: use-after-free in udf_free_inode+0x233/0x2a0 fs/udf/ialloc.c:-1
Read of size 4 at addr ffff88809afb3928 by task syz.3.378/5962

CPU: 1 PID: 5962 Comm: syz.3.378 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 le32_add_cpu include/linux/byteorder/generic.h:151 [inline]
 udf_free_inode+0x233/0x2a0 fs/udf/ialloc.c:-1
 evict+0x4b6/0x8b0 fs/inode.c:647
 do_unlinkat+0x3e7/0x710 fs/namei.c:4363
 __do_sys_unlink fs/namei.c:4404 [inline]
 __se_sys_unlink fs/namei.c:4402 [inline]
 __x64_sys_unlink+0x45/0x50 fs/namei.c:4402
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fa0b72b70d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa0b54ee028 EFLAGS: 00000246 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 00007fa0b753f090 RCX: 00007fa0b72b70d9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000000080
RBP: 00007fa0b734e024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa0b753f128 R14: 00007fa0b753f090 R15: 00007ffc14596318
 </TASK>

The buggy address belongs to the page:
page:ffffea00026becc0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x9afb3
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea00026becc8 ffffea00026becc8 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner info is not present (never set?)

Memory state around the buggy address:
 ffff88809afb3800: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88809afb3880: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88809afb3900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                  ^
 ffff88809afb3980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88809afb3a00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/16 19:05 linux-5.15.y aabd761612db 746171ee .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: use-after-free Read in udf_free_inode
* Struck through repros no longer work on HEAD.