KASAN: slab-out-of-bounds Read in udf_get_filelongad

Status: fixed on 2023/06/08 14:41
Subsystems: udf
[Documentation on labels]
Reported-by: syzbot+60f291a24acecb3c2bd5@syzkaller.appspotmail.com
Fix commit: 53cafe1d6d8e udf: Do not bother merging very long extents
First crash: 1324d, last: 1323d
▶ ▼ Discussions (2)
Title Replies (including bot) Last reply
[PATCH 0/20] udf: Fix various syzbot reports 23 (23) 2022/12/18 05:34
[syzbot] KASAN: slab-out-of-bounds Read in udf_get_filelongad 0 (1) 2022/12/12 07:01
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 KASAN: slab-out-of-bounds Read in udf_get_filelongad 17 2 75d 75d 0/3 upstream: reported on 2026/05/12 16:09
upstream KASAN: slab-out-of-bounds Read in udf_get_filelongad (2) udf 17 C 4 677d 691d 28/29 fixed on 2024/11/12 23:31
linux-4.14 KASAN: use-after-free Read in udf_get_filelongad 19 C 2 1242d 1331d 0/1 upstream: reported C repro on 2022/12/03 02:46
linux-4.19 KASAN: use-after-free Read in udf_get_filelongad 19 C error 2 1335d 1338d 0/1 upstream: reported C repro on 2022/11/26 07:38

Sample crash report:
loop0: detected capacity change from 0 to 2048
UDF-fs: INFO Mounting volume 'LinuxUDF', timestamp 2022/11/22 14:59 (1000)
==================================================================
BUG: KASAN: slab-out-of-bounds in udf_get_filelongad+0x138/0x140 fs/udf/directory.c:235
Read of size 4 at addr ffff88801cd9df58 by task syz-executor397/3629

CPU: 0 PID: 3629 Comm: syz-executor397 Not tainted 6.1.0-rc8-syzkaller-00152-g3ecc37918c80 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:284 [inline]
 print_report+0x15e/0x45d mm/kasan/report.c:395
 kasan_report+0xbf/0x1f0 mm/kasan/report.c:495
 udf_get_filelongad+0x138/0x140 fs/udf/directory.c:235
 udf_current_aext+0x1d6/0x940 fs/udf/inode.c:2206
 udf_next_aext+0x210/0x410 fs/udf/inode.c:2142
 udf_extend_file fs/udf/inode.c:662 [inline]
 udf_setsize+0xa1e/0x1080 fs/udf/inode.c:1249
 udf_setattr+0x4a8/0x5e0 fs/udf/file.c:281
 notify_change+0xcd4/0x1440 fs/attr.c:420
 do_truncate+0x140/0x200 fs/open.c:65
 do_sys_ftruncate+0x53a/0x730 fs/open.c:193
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fd80d1a9909
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 14 00 00 90 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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffef9f8c468 EFLAGS: 00000246 ORIG_RAX: 000000000000004d
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fd80d1a9909
RDX: 00007fd80d1a9909 RSI: 0100000000000000 RDI: 0000000000000005
RBP: 00007fd80d1691a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fd80d169230
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>

Allocated by task 3629:
 kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
 kasan_set_track+0x25/0x30 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:371 [inline]
 ____kasan_kmalloc mm/kasan/common.c:330 [inline]
 __kasan_kmalloc+0xa5/0xb0 mm/kasan/common.c:380
 kasan_kmalloc include/linux/kasan.h:211 [inline]
 __do_kmalloc_node mm/slab_common.c:955 [inline]
 __kmalloc+0x5a/0xd0 mm/slab_common.c:968
 kmalloc include/linux/slab.h:558 [inline]
 kzalloc include/linux/slab.h:689 [inline]
 tomoyo_init_log+0x128e/0x1ed0 security/tomoyo/audit.c:275
 tomoyo_supervisor+0x354/0xf10 security/tomoyo/common.c:2088
 tomoyo_audit_path_number_log security/tomoyo/file.c:235 [inline]
 tomoyo_path_number_perm+0x3f3/0x550 security/tomoyo/file.c:734
 security_file_ioctl+0x54/0xb0 security/security.c:1554
 __do_sys_ioctl fs/ioctl.c:864 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __x64_sys_ioctl+0xb7/0x210 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 3629:
 kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
 kasan_set_track+0x25/0x30 mm/kasan/common.c:52
 kasan_save_free_info+0x2e/0x40 mm/kasan/generic.c:511
 ____kasan_slab_free mm/kasan/common.c:236 [inline]
 ____kasan_slab_free+0x160/0x1c0 mm/kasan/common.c:200
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1724 [inline]
 slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1750
 slab_free mm/slub.c:3661 [inline]
 __kmem_cache_free+0xaf/0x3b0 mm/slub.c:3674
 tomoyo_supervisor+0x375/0xf10 security/tomoyo/common.c:2140
 tomoyo_audit_path_number_log security/tomoyo/file.c:235 [inline]
 tomoyo_path_number_perm+0x3f3/0x550 security/tomoyo/file.c:734
 security_file_ioctl+0x54/0xb0 security/security.c:1554
 __do_sys_ioctl fs/ioctl.c:864 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __x64_sys_ioctl+0xb7/0x210 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff88801cd9dc00
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 344 bytes to the right of
 512-byte region [ffff88801cd9dc00, ffff88801cd9de00)

The buggy address belongs to the physical page:
page:ffffea0000736700 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1cd9c
head:ffffea0000736700 order:2 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 ffffea00007b0700 dead000000000002 ffff888012041c80
raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 209, tgid 209 (kworker/u4:1), ts 5723325076, free_ts 0
 prep_new_page mm/page_alloc.c:2539 [inline]
 get_page_from_freelist+0x10b5/0x2d50 mm/page_alloc.c:4291
 __alloc_pages+0x1cb/0x5b0 mm/page_alloc.c:5558
 alloc_pages+0x1aa/0x270 mm/mempolicy.c:2285
 alloc_slab_page mm/slub.c:1794 [inline]
 allocate_slab+0x25f/0x350 mm/slub.c:1939
 new_slab mm/slub.c:1992 [inline]
 ___slab_alloc+0xa91/0x1400 mm/slub.c:3180
 __slab_alloc.constprop.0+0x56/0xa0 mm/slub.c:3279
 slab_alloc_node mm/slub.c:3364 [inline]
 __kmem_cache_alloc_node+0x199/0x3e0 mm/slub.c:3437
 kmalloc_trace+0x26/0x60 mm/slab_common.c:1045
 kmalloc include/linux/slab.h:553 [inline]
 kzalloc include/linux/slab.h:689 [inline]
 alloc_bprm+0x51/0x900 fs/exec.c:1508
 kernel_execve+0xaf/0x500 fs/exec.c:1967
 call_usermodehelper_exec_async+0x2e7/0x580 kernel/umh.c:113
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88801cd9de00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88801cd9de80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88801cd9df00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                                    ^
 ffff88801cd9df80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88801cd9e000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2022/12/10 19:47 upstream 3ecc37918c80 67be1ae7 .config strace log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-kasan-gce-root KASAN: slab-out-of-bounds Read in udf_get_filelongad
2022/12/11 17:39 upstream 4cee37b3a4e6 67be1ae7 .config console log report info ci-upstream-kasan-gce-smack-root KASAN: slab-out-of-bounds Read in udf_get_filelongad
* Struck through repros no longer work on HEAD.