Re: [syzbot] [net?] KASAN: slab-use-after-free Write in l2tp_session_delete

[James Chapman <jchapman@katalix.com>]

On 25/06/2024 14:25, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    185d72112b95 net: xilinx: axienet: Enable multicast by def..
> git tree:       net-next
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=129911fa980000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=e78fc116033e0ab7
> dashboard link: https://syzkaller.appspot.com/bug?extid=c041b4ce3a6dfd1e63e2
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12521b9c980000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1062bd46980000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/e84f50e44254/disk-185d7211.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/df64b575cc01/vmlinux-185d7211.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/16ad5d1d433b/bzImage-185d7211.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+c041b4ce3a6dfd1e63e2@syzkaller.appspotmail.com
> 
> ==================================================================
> BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
> BUG: KASAN: slab-use-after-free in test_and_set_bit include/asm-generic/bitops/instrumented-atomic.h:71 [inline]
> BUG: KASAN: slab-use-after-free in l2tp_session_delete+0x28/0x9e0 net/l2tp/l2tp_core.c:1639
> Write of size 8 at addr ffff88802aaf5808 by task kworker/u8:11/2523

I'll look at this.