[Android 5.10] KASAN: use-after-free Read in lock_get_status (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: dad37bbb13a8 Merge 5.10.251 into android13-5.10-lts
git tree: android13-5.10-lts
console output: https://syzkaller.appspot.com/x/log.txt?x=12d4d0ba580000
kernel config: https://syzkaller.appspot.com/x/.config?x=ef167f989dba92e
dashboard link: https://syzkaller.appspot.com/bug?extid=4a827d2190ba03c464cb
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=111c68d6580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=132a9472580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9d3036bfa4ed/disk-dad37bbb.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1c5a0794fe3b/vmlinux-dad37bbb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5422ae394213/bzImage-dad37bbb.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4a827d...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in file_inode include/linux/fs.h:1343 [inline]
BUG: KASAN: use-after-free in lock_get_status+0x206/0x960 fs/locks.c:2870
Read of size 8 at addr ffff88812b54ac20 by task syz.5.485/1832

CPU: 0 PID: 1832 Comm: syz.5.485 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
__dump_stack+0x21/0x24 lib/dump_stack.c:77
dump_stack_lvl+0x1a7/0x208 lib/dump_stack.c:118
print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
__kasan_report mm/kasan/report.c:435 [inline]
kasan_report+0xe2/0x130 mm/kasan/report.c:452
__asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:309
file_inode include/linux/fs.h:1343 [inline]
lock_get_status+0x206/0x960 fs/locks.c:2870
locks_show+0x1f1/0x2f0 fs/locks.c:2945
seq_read_iter+0x93f/0xd30 fs/seq_file.c:272
proc_reg_read_iter+0x1be/0x290 fs/proc/inode.c:310
call_read_iter include/linux/fs.h:2060 [inline]
new_sync_read fs/read_write.c:415 [inline]
vfs_read+0x62a/0xa60 fs/read_write.c:496
ksys_pread64 fs/read_write.c:686 [inline]
__do_sys_pread64 fs/read_write.c:696 [inline]
__se_sys_pread64 fs/read_write.c:693 [inline]
__x64_sys_pread64+0x197/0x220 fs/read_write.c:693
do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f26db564799
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:00007f26db3c7028 EFLAGS: 00000246 ORIG_RAX: 0000000000000011
RAX: ffffffffffffffda RBX: 00007f26db7ddfa0 RCX: 00007f26db564799
RDX: 00000000000000d1 RSI: 00002000000024c0 RDI: 0000000000000000
RBP: 00007f26db5fabd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000008 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f26db7de038 R14: 00007f26db7ddfa0 R15: 00007ffe7cbd9d98

Allocated by task 1832:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track mm/kasan/common.c:45 [inline]
set_alloc_info mm/kasan/common.c:430 [inline]
__kasan_slab_alloc+0xbd/0xf0 mm/kasan/common.c:463
kasan_slab_alloc include/linux/kasan.h:244 [inline]
slab_post_alloc_hook+0x5d/0x2f0 mm/slab.h:580
slab_alloc_node mm/slub.c:2952 [inline]
slab_alloc mm/slub.c:2960 [inline]
kmem_cache_alloc+0x162/0x2d0 mm/slub.c:2965
kmem_cache_zalloc include/linux/slab.h:657 [inline]
__alloc_file+0x28/0x320 fs/file_table.c:101
alloc_empty_file+0x97/0x180 fs/file_table.c:151
path_openat+0xf5/0x31c0 fs/namei.c:3503
do_filp_open+0x1e2/0x410 fs/namei.c:3544
do_sys_openat2+0x19f/0x750 fs/open.c:1219
do_sys_open fs/open.c:1235 [inline]
__do_sys_openat fs/open.c:1251 [inline]
__se_sys_openat fs/open.c:1246 [inline]
__x64_sys_openat+0x136/0x160 fs/open.c:1246
do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x61/0xcb

Freed by task 1844:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track+0x4a/0x70 mm/kasan/common.c:45
kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370
____kasan_slab_free+0x125/0x160 mm/kasan/common.c:362
__kasan_slab_free+0x11/0x20 mm/kasan/common.c:370
kasan_slab_free include/linux/kasan.h:220 [inline]
slab_free_hook mm/slub.c:1600 [inline]
slab_free_freelist_hook+0xc5/0x190 mm/slub.c:1626
slab_free mm/slub.c:3208 [inline]
kmem_cache_free+0x100/0x2d0 mm/slub.c:3224
file_free_rcu+0x93/0xa0 fs/file_table.c:50
rcu_do_batch+0x4ef/0xab0 kernel/rcu/tree.c:2494
rcu_core+0x577/0xd80 kernel/rcu/tree.c:2735
rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2748
__do_softirq+0x255/0x563 kernel/softirq.c:309

Last potentially related work creation:
kasan_save_stack+0x3a/0x60 mm/kasan/common.c:38
__kasan_record_aux_stack+0xd2/0x100 mm/kasan/generic.c:348
kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:358
__call_rcu kernel/rcu/tree.c:2980 [inline]
call_rcu+0x11a/0x10b0 kernel/rcu/tree.c:3054
file_free fs/file_table.c:58 [inline]
__fput+0x5ad/0x770 fs/file_table.c:299
____fput+0x15/0x20 fs/file_table.c:314
task_work_run+0x127/0x190 kernel/task_work.c:189
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_user_mode_loop+0xcb/0xe0 kernel/entry/common.c:172
exit_to_user_mode_prepare+0x76/0xa0 kernel/entry/common.c:199
syscall_exit_to_user_mode+0x1d/0x40 kernel/entry/common.c:274
do_syscall_64+0x3d/0x40 arch/x86/entry/common.c:56
entry_SYSCALL_64_after_hwframe+0x61/0xcb

Second to last potentially related work creation:
kasan_save_stack+0x3a/0x60 mm/kasan/common.c:38
__kasan_record_aux_stack+0xd2/0x100 mm/kasan/generic.c:348
kasan_record_aux_stack+0xe/0x10 mm/kasan/generic.c:353
task_work_add+0x27/0x1e0 kernel/task_work.c:38
fput_many+0xe7/0x1a0 fs/file_table.c:342
fput+0x1a/0x20 fs/file_table.c:358
fdput include/linux/file.h:47 [inline]
__do_sys_fcntl fs/fcntl.c:468 [inline]
__se_sys_fcntl+0x107/0x1b0 fs/fcntl.c:450
__x64_sys_fcntl+0x7b/0x90 fs/fcntl.c:450
do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x61/0xcb

The buggy address belongs to the object at ffff88812b54ac00
which belongs to the cache filp of size 296
The buggy address is located 32 bytes inside of
296-byte region [ffff88812b54ac00, ffff88812b54ad28)
The buggy address belongs to the page:
page:ffffea0004ad5280 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x12b54a
head:ffffea0004ad5280 order:1 compound_mapcount:0
flags: 0x4000000000010200(slab|head)
raw: 4000000000010200 ffffea00043bbc80 0000000300000003 ffff88810018a780
raw: 0000000000000000 0000000000150015 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 94, ts 27371481521, free_ts 0
set_page_owner include/linux/page_owner.h:35 [inline]
post_alloc_hook mm/page_alloc.c:2456 [inline]
prep_new_page+0x179/0x180 mm/page_alloc.c:2462
get_page_from_freelist+0x223b/0x23d0 mm/page_alloc.c:4254
__alloc_pages_nodemask+0x290/0x620 mm/page_alloc.c:5370
alloc_slab_page mm/slub.c:-1 [inline]
allocate_slab mm/slub.c:1813 [inline]
new_slab+0x84/0x3f0 mm/slub.c:1874
new_slab_objects mm/slub.c:2632 [inline]
___slab_alloc+0x2a6/0x450 mm/slub.c:2796
__slab_alloc+0x63/0xa0 mm/slub.c:2836
slab_alloc_node mm/slub.c:2918 [inline]
slab_alloc mm/slub.c:2960 [inline]
kmem_cache_alloc+0x1ac/0x2d0 mm/slub.c:2965
kmem_cache_zalloc include/linux/slab.h:657 [inline]
__alloc_file+0x28/0x320 fs/file_table.c:101
alloc_empty_file+0x97/0x180 fs/file_table.c:151
path_openat+0xf5/0x31c0 fs/namei.c:3503
do_filp_open+0x1e2/0x410 fs/namei.c:3544
do_sys_openat2+0x19f/0x750 fs/open.c:1219
do_sys_open fs/open.c:1235 [inline]
__do_sys_openat fs/open.c:1251 [inline]
__se_sys_openat fs/open.c:1246 [inline]
__x64_sys_openat+0x136/0x160 fs/open.c:1246
do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x61/0xcb
page_owner free stack trace missing

Memory state around the buggy address:
ffff88812b54ab00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88812b54ab80: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc
>ffff88812b54ac00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88812b54ac80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88812b54ad00: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc
==================================================================


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