KASAN: use-after-free Read in chrdev_open

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: b34934d4 UPSTREAM: binder: fix UAF when releasing todo list
git tree: android12-5.4
console output: https://syzkaller.appspot.com/x/log.txt?x=1700665f900000
kernel config: https://syzkaller.appspot.com/x/.config?x=a4350d495e02ca3d
dashboard link: https://syzkaller.appspot.com/bug?extid=b481b1e67a35141c5ba0
compiler: Android (6032204 based on r370808) clang version 10.0.1 (https://android.googlesource.com/toolchain/llvm-project 6e765c10313d15c02ab29977a82938f66742c3a9)

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b481b1...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in __list_add_valid+0x36/0xc0 lib/list_debug.c:23
Read of size 8 at addr ffff88818b948600 by task syz-executor.4/11881

CPU: 1 PID: 11881 Comm: syz-executor.4 Not tainted 5.4.72-syzkaller-00299-gb34934d40c49 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1b0/0x21e lib/dump_stack.c:118
print_address_description+0x96/0x5d0 mm/kasan/report.c:374
__kasan_report+0x14b/0x1c0 mm/kasan/report.c:506
kasan_report+0x27/0x50 mm/kasan/common.c:634
__list_add_valid+0x36/0xc0 lib/list_debug.c:23
__list_add include/linux/list.h:60 [inline]
list_add include/linux/list.h:79 [inline]
chrdev_open+0x292/0x670 fs/char_dev.c:396
do_dentry_open+0x8fa/0x1070 fs/open.c:797
do_last fs/namei.c:3495 [inline]
path_openat+0x165b/0x4270 fs/namei.c:3612
do_filp_open+0x1f7/0x430 fs/namei.c:3642
do_sys_open+0x343/0x620 fs/open.c:1094
do_syscall_64+0xcb/0x150 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45de59
Code: 0d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 db b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f16b632cc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000022a40 RCX: 000000000045de59
RDX: 0000000000000000 RSI: 0000000020002000 RDI: ffffffffffffff9c
RBP: 000000000118c010 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118bfd4
R13: 00007ffe58460eff R14: 00007f16b632d9c0 R15: 000000000118bfd4

Allocated by task 11820:
save_stack mm/kasan/common.c:69 [inline]
set_track mm/kasan/common.c:77 [inline]
__kasan_kmalloc+0x117/0x1b0 mm/kasan/common.c:510
slab_post_alloc_hook mm/slab.h:584 [inline]
slab_alloc_node mm/slub.c:2803 [inline]
slab_alloc mm/slub.c:2811 [inline]
kmem_cache_alloc+0x1d5/0x250 mm/slub.c:2816
fuse_alloc_inode+0x20/0x1f0 fs/fuse/inode.c:76
alloc_inode fs/inode.c:232 [inline]
iget5_locked+0xa2/0x3e0 fs/inode.c:1148
fuse_iget+0xf0/0x850 fs/fuse/inode.c:296
fuse_lookup_name+0x63e/0x7e0 fs/fuse/dir.c:363
fuse_lookup+0xfb/0x4d0 fs/fuse/dir.c:390
fuse_atomic_open+0x149/0x1470 fs/fuse/dir.c:533
atomic_open fs/namei.c:3147 [inline]
lookup_open fs/namei.c:3279 [inline]
do_last fs/namei.c:3401 [inline]
path_openat+0x2028/0x4270 fs/namei.c:3612
do_filp_open+0x1f7/0x430 fs/namei.c:3642
do_sys_open+0x343/0x620 fs/open.c:1094
do_syscall_64+0xcb/0x150 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 9:
save_stack mm/kasan/common.c:69 [inline]
set_track mm/kasan/common.c:77 [inline]
kasan_set_free_info mm/kasan/common.c:332 [inline]
__kasan_slab_free+0x168/0x220 mm/kasan/common.c:471
slab_free_hook mm/slub.c:1453 [inline]
slab_free_freelist_hook+0xd0/0x150 mm/slub.c:1486
slab_free mm/slub.c:3051 [inline]
kmem_cache_free+0xac/0x5c0 mm/slub.c:3067
__rcu_reclaim kernel/rcu/rcu.h:222 [inline]
rcu_do_batch kernel/rcu/tree.c:2158 [inline]
rcu_core+0xb30/0x1270 kernel/rcu/tree.c:2378
__do_softirq+0x22e/0x569 kernel/softirq.c:292

The buggy address belongs to the object at ffff88818b9483c0
which belongs to the cache fuse_inode of size 832
The buggy address is located 576 bytes inside of
832-byte region [ffff88818b9483c0, ffff88818b948700)
The buggy address belongs to the page:
page:ffffea00062e5200 refcount:1 mapcount:0 mapping:ffff8881d92b4000 index:0x0 compound_mapcount: 0
flags: 0x8000000000010200(slab|head)
raw: 8000000000010200 ffffea00064a4d00 0000000400000004 ffff8881d92b4000
raw: 0000000000000000 0000000080110011 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88818b948500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88818b948580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88818b948600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88818b948680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88818b948700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.