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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3ef6ca4f354c checksyscalls: Unconditionally ignore fstat{,..
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux.git fixes
console output: https://syzkaller.appspot.com/x/log.txt?x=10af45ecb00000
kernel config: https://syzkaller.appspot.com/x/.config?x=6127780e3f4c1093
dashboard link: https://syzkaller.appspot.com/bug?extid=854216469352268c71b7
compiler: riscv64-linux-gnu-gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
userspace arch: riscv64
CC: [boqun...@gmail.com linux-...@vger.kernel.org lon...@redhat.com mi...@redhat.com pet...@infradead.org wi...@kernel.org]

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+854216...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-out-of-bounds in __bfs+0xea/0x300 kernel/locking/lockdep.c:1696
Read of size 8 at addr ffffffe00e8bffe0 by task syz-executor.0/5818

CPU: 0 PID: 5818 Comm: syz-executor.0 Not tainted 5.15.0-rc1-syzkaller #0
Hardware name: riscv-virtio,qemu (DT)
Call Trace:
[<ffffffff8000957e>] dump_backtrace+0x2e/0x3c arch/riscv/kernel/stacktrace.c:112

Allocated by task 140279808:
(stack is not available)

Freed by task 13624:
(stack is not available)

The buggy address belongs to the object at ffffffe00e8bf800
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 992 bytes to the right of
1024-byte region [ffffffe00e8bf800, ffffffe00e8bfc00)
The buggy address belongs to the page:
page:ffffffcf023aae00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x8eab8
head:ffffffcf023aae00 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xffe000000010200(slab|head|node=0|zone=0|lastcpupid=0x7ff)
raw: 0ffe000000010200 0000000000000100 0000000000000122 ffffffe005601dc0
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 2021, ts 3184747689000, free_ts 3181123489900
page_owner allocation stack trace missing
page_owner free stack trace missing

Memory state around the buggy address:
ffffffe00e8bfe80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffffffe00e8bff00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffffffe00e8bff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffffffe00e8c0000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffffffe00e8c0080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
Dead loop on virtual device ipvlan1, fix it urgently!


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[syzbot]

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