BUG: unable to handle kernel NULL pointer dereference in call_rcu

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 614cb589 Merge tag 'acpi-5.11-rc1-2' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10a82a50d00000
kernel config: https://syzkaller.appspot.com/x/.config?x=bf519e1e96191576
dashboard link: https://syzkaller.appspot.com/bug?extid=9d3ede723bdc58553f13
compiler: gcc (GCC) 10.1.0-syz 20200507
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11830e93500000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13d92057500000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9d3ede...@syzkaller.appspotmail.com

BUG: kernel NULL pointer dereference, address: 0000000000000008
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 2d993067 P4D 2d993067 PUD 19a3c067 PMD 0
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 3852 Comm: kworker/1:2 Not tainted 5.10.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events free_ipc
RIP: 0010:kasan_record_aux_stack+0x77/0xb0 mm/kasan/generic.c:341
Code: 48 f7 fe 8b 47 24 49 89 f0 48 29 d3 8d 70 ff 41 0f af f0 48 01 ce 48 39 f3 48 0f 46 f3 e8 81 e9 ff ff bf 00 08 00 00 48 89 c3 <8b> 40 08 89 43 0c e8 1e e6 ff ff 89 43 08 5b c3 48 8b 50 08 48 c7
RSP: 0018:ffffc90002e6fae8 EFLAGS: 00010046
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff888039800000
RDX: 0000000000000078 RSI: ffff888039800000 RDI: 0000000000000800
RBP: ffffffff837ef3a0 R08: 0000000000400000 R09: 000000000000002e
R10: ffffffff8132b7ea R11: 000000000000003f R12: 0000000000035b40
R13: ffff888039800088 R14: ffffc90002e6fc08 R15: 0000000000000200
FS: 0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000008 CR3: 0000000011841000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
__call_rcu kernel/rcu/tree.c:2965 [inline]
call_rcu+0xbb/0x710 kernel/rcu/tree.c:3038
ipc_rcu_putref+0x83/0xb0 ipc/util.c:505
freeary+0x139c/0x1b30 ipc/sem.c:1188
free_ipcs+0x98/0x1e0 ipc/namespace.c:112
sem_exit_ns+0x1b/0x40 ipc/sem.c:260
free_ipc_ns ipc/namespace.c:124 [inline]
free_ipc+0xf8/0x200 ipc/namespace.c:141
process_one_work+0x98d/0x1630 kernel/workqueue.c:2275
worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
kthread+0x3b1/0x4a0 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
Modules linked in:
CR2: 0000000000000008
---[ end trace 28dc093e61d44dc2 ]---
RIP: 0010:kasan_record_aux_stack+0x77/0xb0 mm/kasan/generic.c:341
Code: 48 f7 fe 8b 47 24 49 89 f0 48 29 d3 8d 70 ff 41 0f af f0 48 01 ce 48 39 f3 48 0f 46 f3 e8 81 e9 ff ff bf 00 08 00 00 48 89 c3 <8b> 40 08 89 43 0c e8 1e e6 ff ff 89 43 08 5b c3 48 8b 50 08 48 c7
RSP: 0018:ffffc90002e6fae8 EFLAGS: 00010046
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff888039800000
RDX: 0000000000000078 RSI: ffff888039800000 RDI: 0000000000000800
RBP: ffffffff837ef3a0 R08: 0000000000400000 R09: 000000000000002e
R10: ffffffff8132b7ea R11: 000000000000003f R12: 0000000000035b40
R13: ffff888039800088 R14: ffffc90002e6fc08 R15: 0000000000000200
FS: 0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000008 CR3: 0000000011841000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
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[Andrew Morton]

(cc KASAN developers)

[Dmitry Vyukov]

/\/\/\/\On Sun, Dec 27, 2020 at 8:45 PM Andrew Morton

<ak...@linux-foundation.org> wrote:
>
> (cc KASAN developers)
>
> On Sat, 26 Dec 2020 15:25:14 -0800 syzbot <syzbot+9d3ede...@syzkaller.appspotmail.com> wrote:
>
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit: 614cb589 Merge tag 'acpi-5.11-rc1-2' of git://git.kernel.o..
> > git tree: upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=10a82a50d00000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=bf519e1e96191576
> > dashboard link: https://syzkaller.appspot.com/bug?extid=9d3ede723bdc58553f13
> > compiler: gcc (GCC) 10.1.0-syz 20200507
> > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11830e93500000
> > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13d92057500000
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+9d3ede...@syzkaller.appspotmail.com
> >
> > BUG: kernel NULL pointer dereference, address: 0000000000000008
> > #PF: supervisor read access in kernel mode
> > #PF: error_code(0x0000) - not-present page
> > PGD 2d993067 P4D 2d993067 PUD 19a3c067 PMD 0
> > Oops: 0000 [#1] PREEMPT SMP KASAN
> > CPU: 1 PID: 3852 Comm: kworker/1:2 Not tainted 5.10.0-syzkaller #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > Workqueue: events free_ipc
> > RIP: 0010:kasan_record_aux_stack+0x77/0xb0 mm/kasan/generic.c:341

+Walter, Andrey

void kasan_record_aux_stack(void *addr)
{
...
alloc_meta = kasan_get_alloc_meta(cache, object);
alloc_meta->aux_stack[1] = alloc_meta->aux_stack[0];

/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
It crashes on NULL deref here, I assume alloc_meta is NULL. We may not
have it for some slabs. Do we miss a NULL check here?

[Walter Wu]

Hi Dmitry,

Yes, I will send a patch to fix it.

Thanks for your suggestion.

Walter

[syzbot]

syzbot has bisected this issue to:

commit 97593cad003c668e2532cb2939a24a031f8de52d
Author: Andrey Konovalov <andre...@google.com>
Date: Tue Dec 22 20:03:28 2020 +0000

kasan: sanitize objects when metadata doesn't fit

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=106689b6d00000
start commit: 614cb589 Merge tag 'acpi-5.11-rc1-2' of git://git.kernel.o..
git tree: upstream
final oops: https://syzkaller.appspot.com/x/report.txt?x=126689b6d00000
console output: https://syzkaller.appspot.com/x/log.txt?x=146689b6d00000

kernel config: https://syzkaller.appspot.com/x/.config?x=bf519e1e96191576
dashboard link: https://syzkaller.appspot.com/bug?extid=9d3ede723bdc58553f13

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11830e93500000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13d92057500000

Reported-by: syzbot+9d3ede...@syzkaller.appspotmail.com
Fixes: 97593cad003c ("kasan: sanitize objects when metadata doesn't fit")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

[Andrey Konovalov]

#syz fix: kasan: fix null pointer dereference in kasan_record_aux_stack