Re: KASAN: use-after-free Read in sk_psock_link_pop

[Daniel Borkmann]

On 10/19/2018 05:54 PM, syzbot wrote:
> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:ÂÂÂ 3a3295bfa6f4 Merge branch 'sctp-fix-sk_wmem_queued-and-use..
> git tree:ÂÂÂÂÂÂ net-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=10a09791400000
> kernel config:Â https://syzkaller.appspot.com/x/.config?x=133950703f7759f9
> dashboard link: https://syzkaller.appspot.com/bug?extid=1651eee005f9de26ec35
> compiler:ÂÂÂÂÂÂ gcc (GCC) 8.0.1 20180413 (experimental)
> 
> Unfortunately, I don't have any reproducer for this crash yet.
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+1651eee005f9de26ec35@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> __nla_parse: 2 callbacks suppressed
> netlink: 20 bytes leftover after parsing attributes in process `syz-executor0'.
> ==================================================================
> BUG: KASAN: use-after-free in __lock_acquire+0x37c2/0x4ec0 kernel/locking/lockdep.c:3290
> Read of size 8 at addr ffff8801bcae2ff8 by task syz-executor3/30186
> 
> CPU: 0 PID: 30186 Comm: syz-executor3 Not tainted 4.19.0-rc7+ #266
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
> Â__dump_stack lib/dump_stack.c:77 [inline]
> Âdump_stack+0x1c4/0x2b4 lib/dump_stack.c:113
> Âprint_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256
> Âkasan_report_error mm/kasan/report.c:354 [inline]
> Âkasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412
> Â__asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
> Â__lock_acquire+0x37c2/0x4ec0 kernel/locking/lockdep.c:3290
> Âlock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3900
> Â__raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
> Â_raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:168
> Âspin_lock_bh include/linux/spinlock.h:334 [inline]
[...]

Looking into it ...