* WARNING: refcount bug in sock_wfree (2)
@ 2019-10-14 2:49 syzbot
2019-10-14 3:25 ` Jens Axboe
0 siblings, 1 reply; 3+ messages in thread
From: syzbot @ 2019-10-14 2:49 UTC (permalink / raw)
To: axboe, davem, hare, jmoyer, linux-block, linux-fsdevel,
linux-kernel, netdev, syzkaller-bugs, viro
Hello,
syzbot found the following crash on:
HEAD commit: 442630f6 Add linux-next specific files for 20191008
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=158fa6bf600000
kernel config: https://syzkaller.appspot.com/x/.config?x=af1bfeef713eefdd
dashboard link: https://syzkaller.appspot.com/bug?extid=c0ba5b9e742f049a2edf
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15a861b3600000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1769f48b600000
The bug was bisected to:
commit 6c080ff07363389cb4092193eb333639f0392b8c
Author: Jens Axboe <axboe@kernel.dk>
Date: Thu Oct 3 14:11:03 2019 +0000
io_uring: allow sparse fixed file sets
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1344b993600000
final crash: https://syzkaller.appspot.com/x/report.txt?x=10c4b993600000
console output: https://syzkaller.appspot.com/x/log.txt?x=1744b993600000
IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+c0ba5b9e742f049a2edf@syzkaller.appspotmail.com
Fixes: 6c080ff07363 ("io_uring: allow sparse fixed file sets")
------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 0 PID: 8691 at lib/refcount.c:190
refcount_sub_and_test_checked lib/refcount.c:190 [inline]
WARNING: CPU: 0 PID: 8691 at lib/refcount.c:190
refcount_sub_and_test_checked+0x1d0/0x200 lib/refcount.c:180
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 8691 Comm: syz-executor322 Not tainted 5.4.0-rc2-next-20191008
#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+0x172/0x1f0 lib/dump_stack.c:113
panic+0x2e3/0x75c kernel/panic.c:221
__warn.cold+0x2f/0x35 kernel/panic.c:582
report_bug+0x289/0x300 lib/bug.c:195
fixup_bug arch/x86/kernel/traps.c:174 [inline]
fixup_bug arch/x86/kernel/traps.c:169 [inline]
do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:267
do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:286
invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1028
RIP: 0010:refcount_sub_and_test_checked lib/refcount.c:190 [inline]
RIP: 0010:refcount_sub_and_test_checked+0x1d0/0x200 lib/refcount.c:180
Code: 1d b0 f0 7f 06 31 ff 89 de e8 6c d7 30 fe 84 db 75 94 e8 23 d6 30 fe
48 c7 c7 20 81 e6 87 c6 05 90 f0 7f 06 01 e8 e8 15 02 fe <0f> 0b e9 75 ff
ff ff e8 04 d6 30 fe e9 6e ff ff ff 48 89 df e8 e7
RSP: 0018:ffff8880a8267a28 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff815cb676 RDI: ffffed101504cf37
RBP: ffff8880a8267ac0 R08: ffff888090e363c0 R09: fffffbfff14eeb42
R10: fffffbfff14eeb41 R11: ffffffff8a775a0f R12: 00000000fffffd02
R13: 0000000000000001 R14: ffff8880a8267a98 R15: 0000000000000001
sock_wfree+0x10c/0x190 net/core/sock.c:1958
unix_destruct_scm+0x115/0x170 net/unix/scm.c:149
io_destruct_skb+0x62/0x80 fs/io_uring.c:2995
skb_release_head_state+0xeb/0x260 net/core/skbuff.c:652
skb_release_all+0x16/0x60 net/core/skbuff.c:663
__kfree_skb net/core/skbuff.c:679 [inline]
kfree_skb net/core/skbuff.c:697 [inline]
kfree_skb+0x101/0x3c0 net/core/skbuff.c:691
__io_sqe_files_scm+0x429/0x640 fs/io_uring.c:3049
io_sqe_files_scm fs/io_uring.c:3071 [inline]
io_sqe_files_register fs/io_uring.c:3154 [inline]
__io_uring_register+0x1f69/0x2d70 fs/io_uring.c:4152
__do_sys_io_uring_register fs/io_uring.c:4204 [inline]
__se_sys_io_uring_register fs/io_uring.c:4186 [inline]
__x64_sys_io_uring_register+0x193/0x1f0 fs/io_uring.c:4186
do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x440279
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 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 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffeeedc31e8 EFLAGS: 00000246 ORIG_RAX: 00000000000001ab
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440279
RDX: 0000000020000280 RSI: 0000000000000002 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000401b00
R13: 0000000000401b90 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..
---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.
syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: WARNING: refcount bug in sock_wfree (2)
2019-10-14 2:49 WARNING: refcount bug in sock_wfree (2) syzbot
@ 2019-10-14 3:25 ` Jens Axboe
2019-10-14 15:01 ` Jens Axboe
0 siblings, 1 reply; 3+ messages in thread
From: Jens Axboe @ 2019-10-14 3:25 UTC (permalink / raw)
To: syzbot, davem, hare, jmoyer, linux-block, linux-fsdevel,
linux-kernel, netdev, syzkaller-bugs, viro
On 10/13/19 8:49 PM, syzbot wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit: 442630f6 Add linux-next specific files for 20191008
> git tree: linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=158fa6bf600000
> kernel config: https://syzkaller.appspot.com/x/.config?x=af1bfeef713eefdd
> dashboard link: https://syzkaller.appspot.com/bug?extid=c0ba5b9e742f049a2edf
> compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15a861b3600000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1769f48b600000
>
> The bug was bisected to:
>
> commit 6c080ff07363389cb4092193eb333639f0392b8c
> Author: Jens Axboe <axboe@kernel.dk>
> Date: Thu Oct 3 14:11:03 2019 +0000
>
> io_uring: allow sparse fixed file sets
>
> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1344b993600000
> final crash: https://syzkaller.appspot.com/x/report.txt?x=10c4b993600000
> console output: https://syzkaller.appspot.com/x/log.txt?x=1744b993600000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+c0ba5b9e742f049a2edf@syzkaller.appspotmail.com
> Fixes: 6c080ff07363 ("io_uring: allow sparse fixed file sets")
>
> ------------[ cut here ]------------
> refcount_t: underflow; use-after-free.
> WARNING: CPU: 0 PID: 8691 at lib/refcount.c:190
> refcount_sub_and_test_checked lib/refcount.c:190 [inline]
> WARNING: CPU: 0 PID: 8691 at lib/refcount.c:190
> refcount_sub_and_test_checked+0x1d0/0x200 lib/refcount.c:180
> Kernel panic - not syncing: panic_on_warn set ...
> CPU: 0 PID: 8691 Comm: syz-executor322 Not tainted 5.4.0-rc2-next-20191008
> #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+0x172/0x1f0 lib/dump_stack.c:113
> panic+0x2e3/0x75c kernel/panic.c:221
> __warn.cold+0x2f/0x35 kernel/panic.c:582
> report_bug+0x289/0x300 lib/bug.c:195
> fixup_bug arch/x86/kernel/traps.c:174 [inline]
> fixup_bug arch/x86/kernel/traps.c:169 [inline]
> do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:267
> do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:286
> invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1028
> RIP: 0010:refcount_sub_and_test_checked lib/refcount.c:190 [inline]
> RIP: 0010:refcount_sub_and_test_checked+0x1d0/0x200 lib/refcount.c:180
> Code: 1d b0 f0 7f 06 31 ff 89 de e8 6c d7 30 fe 84 db 75 94 e8 23 d6 30 fe
> 48 c7 c7 20 81 e6 87 c6 05 90 f0 7f 06 01 e8 e8 15 02 fe <0f> 0b e9 75 ff
> ff ff e8 04 d6 30 fe e9 6e ff ff ff 48 89 df e8 e7
> RSP: 0018:ffff8880a8267a28 EFLAGS: 00010282
> RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
> RDX: 0000000000000000 RSI: ffffffff815cb676 RDI: ffffed101504cf37
> RBP: ffff8880a8267ac0 R08: ffff888090e363c0 R09: fffffbfff14eeb42
> R10: fffffbfff14eeb41 R11: ffffffff8a775a0f R12: 00000000fffffd02
> R13: 0000000000000001 R14: ffff8880a8267a98 R15: 0000000000000001
> sock_wfree+0x10c/0x190 net/core/sock.c:1958
> unix_destruct_scm+0x115/0x170 net/unix/scm.c:149
> io_destruct_skb+0x62/0x80 fs/io_uring.c:2995
> skb_release_head_state+0xeb/0x260 net/core/skbuff.c:652
> skb_release_all+0x16/0x60 net/core/skbuff.c:663
> __kfree_skb net/core/skbuff.c:679 [inline]
> kfree_skb net/core/skbuff.c:697 [inline]
> kfree_skb+0x101/0x3c0 net/core/skbuff.c:691
> __io_sqe_files_scm+0x429/0x640 fs/io_uring.c:3049
> io_sqe_files_scm fs/io_uring.c:3071 [inline]
> io_sqe_files_register fs/io_uring.c:3154 [inline]
> __io_uring_register+0x1f69/0x2d70 fs/io_uring.c:4152
> __do_sys_io_uring_register fs/io_uring.c:4204 [inline]
> __se_sys_io_uring_register fs/io_uring.c:4186 [inline]
> __x64_sys_io_uring_register+0x193/0x1f0 fs/io_uring.c:4186
> do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x440279
> Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 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 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007ffeeedc31e8 EFLAGS: 00000246 ORIG_RAX: 00000000000001ab
> RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440279
> RDX: 0000000020000280 RSI: 0000000000000002 RDI: 0000000000000003
> RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8
> R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000401b00
> R13: 0000000000401b90 R14: 0000000000000000 R15: 0000000000000000
> Kernel Offset: disabled
> Rebooting in 86400 seconds..
I think this will do it, but that's just from looking at the code,
haven't tried to reproduce anything yet.
I'll take a closer look tomorrow and verify.
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 0b20b3599b01..52daeb71ee27 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -3016,7 +3016,6 @@ static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset)
}
skb->sk = sk;
- skb->destructor = io_destruct_skb;
nr_files = 0;
fpl->user = get_uid(ctx->user);
@@ -3031,6 +3030,7 @@ static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset)
if (nr_files) {
fpl->max = fpl->count = nr_files;
UNIXCB(skb).fp = fpl;
+ skb->destructor = io_destruct_skb;
refcount_add(skb->truesize, &sk->sk_wmem_alloc);
skb_queue_head(&sk->sk_receive_queue, skb);
--
Jens Axboe
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: WARNING: refcount bug in sock_wfree (2)
2019-10-14 3:25 ` Jens Axboe
@ 2019-10-14 15:01 ` Jens Axboe
0 siblings, 0 replies; 3+ messages in thread
From: Jens Axboe @ 2019-10-14 15:01 UTC (permalink / raw)
To: syzbot, davem, hare, jmoyer, linux-block, linux-fsdevel,
linux-kernel, netdev, syzkaller-bugs, viro
On 10/13/19 9:25 PM, Jens Axboe wrote:
> On 10/13/19 8:49 PM, syzbot wrote:
>> Hello,
>>
>> syzbot found the following crash on:
>>
>> HEAD commit: 442630f6 Add linux-next specific files for 20191008
>> git tree: linux-next
>> console output: https://syzkaller.appspot.com/x/log.txt?x=158fa6bf600000
>> kernel config: https://syzkaller.appspot.com/x/.config?x=af1bfeef713eefdd
>> dashboard link: https://syzkaller.appspot.com/bug?extid=c0ba5b9e742f049a2edf
>> compiler: gcc (GCC) 9.0.0 20181231 (experimental)
>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15a861b3600000
>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1769f48b600000
>>
>> The bug was bisected to:
>>
>> commit 6c080ff07363389cb4092193eb333639f0392b8c
>> Author: Jens Axboe <axboe@kernel.dk>
>> Date: Thu Oct 3 14:11:03 2019 +0000
>>
>> io_uring: allow sparse fixed file sets
>>
>> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1344b993600000
>> final crash: https://syzkaller.appspot.com/x/report.txt?x=10c4b993600000
>> console output: https://syzkaller.appspot.com/x/log.txt?x=1744b993600000
>>
>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>> Reported-by: syzbot+c0ba5b9e742f049a2edf@syzkaller.appspotmail.com
>> Fixes: 6c080ff07363 ("io_uring: allow sparse fixed file sets")
>>
>> ------------[ cut here ]------------
>> refcount_t: underflow; use-after-free.
>> WARNING: CPU: 0 PID: 8691 at lib/refcount.c:190
>> refcount_sub_and_test_checked lib/refcount.c:190 [inline]
>> WARNING: CPU: 0 PID: 8691 at lib/refcount.c:190
>> refcount_sub_and_test_checked+0x1d0/0x200 lib/refcount.c:180
>> Kernel panic - not syncing: panic_on_warn set ...
>> CPU: 0 PID: 8691 Comm: syz-executor322 Not tainted 5.4.0-rc2-next-20191008
>> #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+0x172/0x1f0 lib/dump_stack.c:113
>> panic+0x2e3/0x75c kernel/panic.c:221
>> __warn.cold+0x2f/0x35 kernel/panic.c:582
>> report_bug+0x289/0x300 lib/bug.c:195
>> fixup_bug arch/x86/kernel/traps.c:174 [inline]
>> fixup_bug arch/x86/kernel/traps.c:169 [inline]
>> do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:267
>> do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:286
>> invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1028
>> RIP: 0010:refcount_sub_and_test_checked lib/refcount.c:190 [inline]
>> RIP: 0010:refcount_sub_and_test_checked+0x1d0/0x200 lib/refcount.c:180
>> Code: 1d b0 f0 7f 06 31 ff 89 de e8 6c d7 30 fe 84 db 75 94 e8 23 d6 30 fe
>> 48 c7 c7 20 81 e6 87 c6 05 90 f0 7f 06 01 e8 e8 15 02 fe <0f> 0b e9 75 ff
>> ff ff e8 04 d6 30 fe e9 6e ff ff ff 48 89 df e8 e7
>> RSP: 0018:ffff8880a8267a28 EFLAGS: 00010282
>> RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
>> RDX: 0000000000000000 RSI: ffffffff815cb676 RDI: ffffed101504cf37
>> RBP: ffff8880a8267ac0 R08: ffff888090e363c0 R09: fffffbfff14eeb42
>> R10: fffffbfff14eeb41 R11: ffffffff8a775a0f R12: 00000000fffffd02
>> R13: 0000000000000001 R14: ffff8880a8267a98 R15: 0000000000000001
>> sock_wfree+0x10c/0x190 net/core/sock.c:1958
>> unix_destruct_scm+0x115/0x170 net/unix/scm.c:149
>> io_destruct_skb+0x62/0x80 fs/io_uring.c:2995
>> skb_release_head_state+0xeb/0x260 net/core/skbuff.c:652
>> skb_release_all+0x16/0x60 net/core/skbuff.c:663
>> __kfree_skb net/core/skbuff.c:679 [inline]
>> kfree_skb net/core/skbuff.c:697 [inline]
>> kfree_skb+0x101/0x3c0 net/core/skbuff.c:691
>> __io_sqe_files_scm+0x429/0x640 fs/io_uring.c:3049
>> io_sqe_files_scm fs/io_uring.c:3071 [inline]
>> io_sqe_files_register fs/io_uring.c:3154 [inline]
>> __io_uring_register+0x1f69/0x2d70 fs/io_uring.c:4152
>> __do_sys_io_uring_register fs/io_uring.c:4204 [inline]
>> __se_sys_io_uring_register fs/io_uring.c:4186 [inline]
>> __x64_sys_io_uring_register+0x193/0x1f0 fs/io_uring.c:4186
>> do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
>> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>> RIP: 0033:0x440279
>> Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 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 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
>> RSP: 002b:00007ffeeedc31e8 EFLAGS: 00000246 ORIG_RAX: 00000000000001ab
>> RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440279
>> RDX: 0000000020000280 RSI: 0000000000000002 RDI: 0000000000000003
>> RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8
>> R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000401b00
>> R13: 0000000000401b90 R14: 0000000000000000 R15: 0000000000000000
>> Kernel Offset: disabled
>> Rebooting in 86400 seconds..
>
> I think this will do it, but that's just from looking at the code,
> haven't tried to reproduce anything yet.
>
> I'll take a closer look tomorrow and verify.
Took a closer look, and verified that this is indeed the issue, and that
the patch does fix it. I'm going to apply this to my for-5.5/io_uring
branch, which is where the offending commit it queued up.
--
Jens Axboe
^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-10-14 2:49 WARNING: refcount bug in sock_wfree (2) syzbot
2019-10-14 3:25 ` Jens Axboe
2019-10-14 15:01 ` Jens Axboe
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