* [syzbot] [net?] divide error in __tcp_select_window (4)
@ 2025-11-25 19:50 syzbot
0 siblings, 0 replies; 5+ messages in thread
From: syzbot @ 2025-11-25 19:50 UTC (permalink / raw)
To: davem, dsahern, edumazet, geliang, horms, kuba, kuniyu,
linux-kernel, matttbe, ncardwell, netdev, pabeni, syzkaller-bugs
Hello,
syzbot found the following issue on:
HEAD commit: e2c20036a887 Merge branch 'devlink-net-mlx5-implement-swp_..
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1164c484580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a881ccda32df4e75
dashboard link: https://syzkaller.appspot.com/bug?extid=3a92d359bc2ec6255a33
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13f8fa12580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=113a5a12580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/07279e689a07/disk-e2c20036.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b13e2e59c1ed/vmlinux-e2c20036.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f6f519394597/bzImage-e2c20036.xz
The issue was bisected to:
commit ae155060247be8dcae3802a95bd1bdf93ab3215d
Author: Paolo Abeni <pabeni@redhat.com>
Date: Tue Nov 18 07:20:24 2025 +0000
mptcp: fix duplicate reset on fastclose
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=11f698b4580000
final oops: https://syzkaller.appspot.com/x/report.txt?x=13f698b4580000
console output: https://syzkaller.appspot.com/x/log.txt?x=15f698b4580000
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3a92d359bc2ec6255a33@syzkaller.appspotmail.com
Fixes: ae155060247b ("mptcp: fix duplicate reset on fastclose")
RBP: 00007ffff9acee10 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007f66e9be5fa0 R14: 00007f66e9be5fa0 R15: 0000000000000006
</TASK>
Oops: divide error: 0000 [#1] SMP KASAN PTI
CPU: 0 UID: 0 PID: 6068 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:__tcp_select_window+0x824/0x1320 net/ipv4/tcp_output.c:3336
Code: ff ff ff 44 89 f1 d3 e0 89 c1 f7 d1 41 01 cc 41 21 c4 e9 a9 00 00 00 e8 ca 49 01 f8 e9 9c 00 00 00 e8 c0 49 01 f8 44 89 e0 99 <f7> 7c 24 1c 41 29 d4 48 bb 00 00 00 00 00 fc ff df e9 80 00 00 00
RSP: 0018:ffffc90003017640 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff88807b469e40
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90003017730 R08: ffff888033268143 R09: 1ffff1100664d028
R10: dffffc0000000000 R11: ffffed100664d029 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS: 000055557faa0500(0000) GS:ffff888126135000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f64a1912ff8 CR3: 0000000072122000 CR4: 00000000003526f0
Call Trace:
<TASK>
tcp_select_window net/ipv4/tcp_output.c:281 [inline]
__tcp_transmit_skb+0xbc7/0x3aa0 net/ipv4/tcp_output.c:1568
tcp_transmit_skb net/ipv4/tcp_output.c:1649 [inline]
tcp_send_active_reset+0x2d1/0x5b0 net/ipv4/tcp_output.c:3836
mptcp_do_fastclose+0x27e/0x380 net/mptcp/protocol.c:2793
mptcp_disconnect+0x238/0x710 net/mptcp/protocol.c:3253
mptcp_sendmsg_fastopen+0x2f8/0x580 net/mptcp/protocol.c:1776
mptcp_sendmsg+0x1774/0x1980 net/mptcp/protocol.c:1855
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg+0xe5/0x270 net/socket.c:742
__sys_sendto+0x3bd/0x520 net/socket.c:2244
__do_sys_sendto net/socket.c:2251 [inline]
__se_sys_sendto net/socket.c:2247 [inline]
__x64_sys_sendto+0xde/0x100 net/socket.c:2247
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f66e998f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffff9acedb8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f66e9be5fa0 RCX: 00007f66e998f749
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007ffff9acee10 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007f66e9be5fa0 R14: 00007f66e9be5fa0 R15: 0000000000000006
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__tcp_select_window+0x824/0x1320 net/ipv4/tcp_output.c:3336
Code: ff ff ff 44 89 f1 d3 e0 89 c1 f7 d1 41 01 cc 41 21 c4 e9 a9 00 00 00 e8 ca 49 01 f8 e9 9c 00 00 00 e8 c0 49 01 f8 44 89 e0 99 <f7> 7c 24 1c 41 29 d4 48 bb 00 00 00 00 00 fc ff df e9 80 00 00 00
RSP: 0018:ffffc90003017640 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff88807b469e40
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90003017730 R08: ffff888033268143 R09: 1ffff1100664d028
R10: dffffc0000000000 R11: ffffed100664d029 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS: 000055557faa0500(0000) GS:ffff888126135000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f64a1912ff8 CR3: 0000000072122000 CR4: 00000000003526f0
----------------
Code disassembly (best guess), 2 bytes skipped:
0: ff 44 89 f1 incl -0xf(%rcx,%rcx,4)
4: d3 e0 shl %cl,%eax
6: 89 c1 mov %eax,%ecx
8: f7 d1 not %ecx
a: 41 01 cc add %ecx,%r12d
d: 41 21 c4 and %eax,%r12d
10: e9 a9 00 00 00 jmp 0xbe
15: e8 ca 49 01 f8 call 0xf80149e4
1a: e9 9c 00 00 00 jmp 0xbb
1f: e8 c0 49 01 f8 call 0xf80149e4
24: 44 89 e0 mov %r12d,%eax
27: 99 cltd
* 28: f7 7c 24 1c idivl 0x1c(%rsp) <-- trapping instruction
2c: 41 29 d4 sub %edx,%r12d
2f: 48 bb 00 00 00 00 00 movabs $0xdffffc0000000000,%rbx
36: fc ff df
39: e9 80 00 00 00 jmp 0xbe
---
This report 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 issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [syzbot] [net?] divide error in __tcp_select_window (4)
[not found] <5a35524e-68b4-4c6e-a0eb-cc7ca21b2d3a@kernel.org>
@ 2025-11-26 11:51 ` syzbot
0 siblings, 0 replies; 5+ messages in thread
From: syzbot @ 2025-11-26 11:51 UTC (permalink / raw)
To: matttbe; +Cc: matttbe, pabeni, syzkaller-bugs, linux-kernel
> Hello,
>
> (+cc Paolo)
>
> On 26/11/2025 12:28, Matthieu Baerts wrote:
>> Hello,
>>
>> (Without other ML's to test a different fix)
>>
>> On 25/11/2025 20:50, syzbot wrote:
>>> Hello,
>>>
>>> syzbot found the following issue on:
>>>
>>> HEAD commit: e2c20036a887 Merge branch 'devlink-net-mlx5-implement-swp_..
>>> git tree: net-next
>>> console output: https://syzkaller.appspot.com/x/log.txt?x=1164c484580000
>>> kernel config: https://syzkaller.appspot.com/x/.config?x=a881ccda32df4e75
>>> dashboard link: https://syzkaller.appspot.com/bug?extid=3a92d359bc2ec6255a33
>>> compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
>>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13f8fa12580000
>>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=113a5a12580000
>>>
>>> Downloadable assets:
>>> disk image: https://storage.googleapis.com/syzbot-assets/07279e689a07/disk-e2c20036.raw.xz
>>> vmlinux: https://storage.googleapis.com/syzbot-assets/b13e2e59c1ed/vmlinux-e2c20036.xz
>>> kernel image: https://storage.googleapis.com/syzbot-assets/f6f519394597/bzImage-e2c20036.xz
>>>
>>> The issue was bisected to:
>>>
>>> commit ae155060247be8dcae3802a95bd1bdf93ab3215d
>>> Author: Paolo Abeni <pabeni@redhat.com>
>>> Date: Tue Nov 18 07:20:24 2025 +0000
>>>
>>> mptcp: fix duplicate reset on fastclose
>>>
>>> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=11f698b4580000
>>> final oops: https://syzkaller.appspot.com/x/report.txt?x=13f698b4580000
>>> console output: https://syzkaller.appspot.com/x/log.txt?x=15f698b4580000
>>>
>>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>>> Reported-by: syzbot+3a92d359bc2ec6255a33@syzkaller.appspotmail.com
>>> Fixes: ae155060247b ("mptcp: fix duplicate reset on fastclose")
>>
>> I *think* this issue might have been fixed by another patch that has
>> been sent recently, see "mptcp: clear scheduled subflows on retransmit":
>>
>>
>> #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/matttbe/net-next.git b4/net-mptcp-clear-sched-rtx
>
>
> Mmh, sorry for the noise, I just noticed the reproducers were apparently
> only working on top of net-next, and my branch was on top of 'net'.
> Sending the patch with net-next as base then.
>
> #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git
"Cheers," does not look like a valid git branch or commit.
>
> Cheers,
> Matt
> --
> Sponsored by the NGI0 Core fund.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [syzbot] [net?] divide error in __tcp_select_window (4)
[not found] <914539f5-5e27-464e-a572-ada0a475d0f1@kernel.org>
@ 2025-11-26 12:20 ` syzbot
2025-11-26 12:22 ` Matthieu Baerts
0 siblings, 1 reply; 5+ messages in thread
From: syzbot @ 2025-11-26 12:20 UTC (permalink / raw)
To: linux-kernel, matttbe, pabeni, syzkaller-bugs
Hello,
syzbot has tested the proposed patch but the reproducer is still triggering an issue:
divide error in __tcp_select_window
RSP: 002b:00007f86321dd038 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f86315e5fa0 RCX: 00007f863138f749
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f86321dd090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007f86315e6038 R14: 00007f86315e5fa0 R15: 00007ffd93c62a18
</TASK>
Oops: divide error: 0000 [#1] SMP KASAN PTI
CPU: 1 UID: 0 PID: 6439 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:__tcp_select_window+0x824/0x1320 net/ipv4/tcp_output.c:3336
Code: ff ff ff 44 89 f1 d3 e0 89 c1 f7 d1 41 01 cc 41 21 c4 e9 a9 00 00 00 e8 da 10 01 f8 e9 9c 00 00 00 e8 d0 10 01 f8 44 89 e0 99 <f7> 7c 24 1c 41 29 d4 48 bb 00 00 00 00 00 fc ff df e9 80 00 00 00
RSP: 0018:ffffc900030a7640 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff8880258abc80
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900030a7730 R08: ffff8880310e8dc3 R09: 1ffff1100621d1b8
R10: dffffc0000000000 R11: ffffed100621d1b9 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS: 00007f86321dd6c0(0000) GS:ffff888126235000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000180 CR3: 000000007e366000 CR4: 00000000003526f0
Call Trace:
<TASK>
tcp_select_window net/ipv4/tcp_output.c:281 [inline]
__tcp_transmit_skb+0xbc7/0x3aa0 net/ipv4/tcp_output.c:1568
tcp_transmit_skb net/ipv4/tcp_output.c:1649 [inline]
tcp_send_active_reset+0x2d1/0x5b0 net/ipv4/tcp_output.c:3836
mptcp_do_fastclose+0x286/0x390 net/mptcp/protocol.c:2896
mptcp_disconnect+0x238/0x730 net/mptcp/protocol.c:3380
mptcp_sendmsg_fastopen+0x2f8/0x580 net/mptcp/protocol.c:1801
mptcp_sendmsg+0x1774/0x1980 net/mptcp/protocol.c:1880
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg+0xe5/0x270 net/socket.c:742
__sys_sendto+0x3bd/0x520 net/socket.c:2244
__do_sys_sendto net/socket.c:2251 [inline]
__se_sys_sendto net/socket.c:2247 [inline]
__x64_sys_sendto+0xde/0x100 net/socket.c:2247
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f863138f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f86321dd038 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f86315e5fa0 RCX: 00007f863138f749
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f86321dd090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007f86315e6038 R14: 00007f86315e5fa0 R15: 00007ffd93c62a18
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__tcp_select_window+0x824/0x1320 net/ipv4/tcp_output.c:3336
Code: ff ff ff 44 89 f1 d3 e0 89 c1 f7 d1 41 01 cc 41 21 c4 e9 a9 00 00 00 e8 da 10 01 f8 e9 9c 00 00 00 e8 d0 10 01 f8 44 89 e0 99 <f7> 7c 24 1c 41 29 d4 48 bb 00 00 00 00 00 fc ff df e9 80 00 00 00
RSP: 0018:ffffc900030a7640 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff8880258abc80
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900030a7730 R08: ffff8880310e8dc3 R09: 1ffff1100621d1b8
R10: dffffc0000000000 R11: ffffed100621d1b9 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS: 00007f86321dd6c0(0000) GS:ffff888126235000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4311661286 CR3: 000000007e366000 CR4: 00000000003526f0
----------------
Code disassembly (best guess), 2 bytes skipped:
0: ff 44 89 f1 incl -0xf(%rcx,%rcx,4)
4: d3 e0 shl %cl,%eax
6: 89 c1 mov %eax,%ecx
8: f7 d1 not %ecx
a: 41 01 cc add %ecx,%r12d
d: 41 21 c4 and %eax,%r12d
10: e9 a9 00 00 00 jmp 0xbe
15: e8 da 10 01 f8 call 0xf80110f4
1a: e9 9c 00 00 00 jmp 0xbb
1f: e8 d0 10 01 f8 call 0xf80110f4
24: 44 89 e0 mov %r12d,%eax
27: 99 cltd
* 28: f7 7c 24 1c idivl 0x1c(%rsp) <-- trapping instruction
2c: 41 29 d4 sub %edx,%r12d
2f: 48 bb 00 00 00 00 00 movabs $0xdffffc0000000000,%rbx
36: fc ff df
39: e9 80 00 00 00 jmp 0xbe
Tested on:
commit: ab084f0b drivers: net: fbnic: Return the true error in..
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git main
console output: https://syzkaller.appspot.com/x/log.txt?x=1317ee92580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a881ccda32df4e75
dashboard link: https://syzkaller.appspot.com/bug?extid=3a92d359bc2ec6255a33
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch: https://syzkaller.appspot.com/x/patch.diff?x=16cb0e12580000
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [syzbot] [net?] divide error in __tcp_select_window (4)
2025-11-26 12:20 ` syzbot
@ 2025-11-26 12:22 ` Matthieu Baerts
0 siblings, 0 replies; 5+ messages in thread
From: Matthieu Baerts @ 2025-11-26 12:22 UTC (permalink / raw)
To: syzbot, linux-kernel, pabeni, syzkaller-bugs
Hello,
On 26/11/2025 13:20, syzbot wrote:
> Hello,
>
> syzbot has tested the proposed patch but the reproducer is still triggering an issue:
> divide error in __tcp_select_window
>
> RSP: 002b:00007f86321dd038 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
> RAX: ffffffffffffffda RBX: 00007f86315e5fa0 RCX: 00007f863138f749
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
> RBP: 00007f86321dd090 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
> R13: 00007f86315e6038 R14: 00007f86315e5fa0 R15: 00007ffd93c62a18
> </TASK>
> Oops: divide error: 0000 [#1] SMP KASAN PTI
> CPU: 1 UID: 0 PID: 6439 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
> RIP: 0010:__tcp_select_window+0x824/0x1320 net/ipv4/tcp_output.c:3336
> Code: ff ff ff 44 89 f1 d3 e0 89 c1 f7 d1 41 01 cc 41 21 c4 e9 a9 00 00 00 e8 da 10 01 f8 e9 9c 00 00 00 e8 d0 10 01 f8 44 89 e0 99 <f7> 7c 24 1c 41 29 d4 48 bb 00 00 00 00 00 fc ff df e9 80 00 00 00
> RSP: 0018:ffffc900030a7640 EFLAGS: 00010293
> RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff8880258abc80
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: ffffc900030a7730 R08: ffff8880310e8dc3 R09: 1ffff1100621d1b8
> R10: dffffc0000000000 R11: ffffed100621d1b9 R12: 0000000000000000
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> FS: 00007f86321dd6c0(0000) GS:ffff888126235000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000200000000180 CR3: 000000007e366000 CR4: 00000000003526f0
> Call Trace:
> <TASK>
> tcp_select_window net/ipv4/tcp_output.c:281 [inline]
> __tcp_transmit_skb+0xbc7/0x3aa0 net/ipv4/tcp_output.c:1568
> tcp_transmit_skb net/ipv4/tcp_output.c:1649 [inline]
> tcp_send_active_reset+0x2d1/0x5b0 net/ipv4/tcp_output.c:3836
> mptcp_do_fastclose+0x286/0x390 net/mptcp/protocol.c:2896
> mptcp_disconnect+0x238/0x730 net/mptcp/protocol.c:3380
> mptcp_sendmsg_fastopen+0x2f8/0x580 net/mptcp/protocol.c:1801
Indeed, my bad, I missed this: it is a different issue involving TFO
(too many 'fast' :) ). A different fix than the one from Paolo -- like
the one sent by Kuniyuki -- is still needed.
Cheers,
Matt
--
Sponsored by the NGI0 Core fund.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [syzbot] [net?] divide error in __tcp_select_window (4)
[not found] <5e24b887-4eb3-474e-9560-fd0c0ffacb8e@kernel.org>
@ 2025-11-26 12:33 ` syzbot
0 siblings, 0 replies; 5+ messages in thread
From: syzbot @ 2025-11-26 12:33 UTC (permalink / raw)
To: linux-kernel, matttbe, syzkaller-bugs
Hello,
syzbot has tested the proposed patch but the reproducer is still triggering an issue:
divide error in __tcp_select_window
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fbc0bc37038 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007fbc0afe5fa0 RCX: 00007fbc0ad8f749
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007fbc0bc37090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fbc0afe6038 R14: 00007fbc0afe5fa0 R15: 00007ffe094ab938
</TASK>
Oops: divide error: 0000 [#1] SMP KASAN PTI
CPU: 0 UID: 0 PID: 6503 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:__tcp_select_window+0x7a2/0x1270 net/ipv4/tcp_output.c:3333
Code: ff ff ff 44 89 e1 d3 e0 89 c1 f7 d1 41 01 ce 41 21 c6 e9 c5 00 00 00 e8 8c c6 01 f8 e9 b8 00 00 00 e8 82 c6 01 f8 44 89 f0 99 <f7> 7c 24 2c 41 29 d6 48 bb 00 00 00 00 00 fc ff df e9 9c 00 00 00
RSP: 0018:ffffc90002e67640 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff88802e693c80
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90002e67730 R08: ffff888027d78143 R09: 1ffff11004faf028
R10: dffffc0000000000 R11: ffffed1004faf029 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffff88802fdc24f0
FS: 00007fbc0bc376c0(0000) GS:ffff888126139000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005587d939f950 CR3: 000000007c31a000 CR4: 00000000003526f0
Call Trace:
<TASK>
tcp_select_window net/ipv4/tcp_output.c:280 [inline]
__tcp_transmit_skb+0xbc7/0x3aa0 net/ipv4/tcp_output.c:1565
tcp_transmit_skb net/ipv4/tcp_output.c:1646 [inline]
tcp_send_active_reset+0x2d1/0x5b0 net/ipv4/tcp_output.c:3828
mptcp_do_fastclose+0x27e/0x380 net/mptcp/protocol.c:2801
mptcp_disconnect+0x238/0x710 net/mptcp/protocol.c:3261
mptcp_sendmsg_fastopen+0x2f8/0x580 net/mptcp/protocol.c:1775
mptcp_sendmsg+0x1774/0x1980 net/mptcp/protocol.c:1854
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg+0xe5/0x270 net/socket.c:742
__sys_sendto+0x3bd/0x520 net/socket.c:2244
__do_sys_sendto net/socket.c:2251 [inline]
__se_sys_sendto net/socket.c:2247 [inline]
__x64_sys_sendto+0xde/0x100 net/socket.c:2247
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbc0ad8f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fbc0bc37038 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007fbc0afe5fa0 RCX: 00007fbc0ad8f749
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007fbc0bc37090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fbc0afe6038 R14: 00007fbc0afe5fa0 R15: 00007ffe094ab938
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__tcp_select_window+0x7a2/0x1270 net/ipv4/tcp_output.c:3333
Code: ff ff ff 44 89 e1 d3 e0 89 c1 f7 d1 41 01 ce 41 21 c6 e9 c5 00 00 00 e8 8c c6 01 f8 e9 b8 00 00 00 e8 82 c6 01 f8 44 89 f0 99 <f7> 7c 24 2c 41 29 d6 48 bb 00 00 00 00 00 fc ff df e9 9c 00 00 00
RSP: 0018:ffffc90002e67640 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff88802e693c80
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90002e67730 R08: ffff888027d78143 R09: 1ffff11004faf028
R10: dffffc0000000000 R11: ffffed1004faf029 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffff88802fdc24f0
FS: 00007fbc0bc376c0(0000) GS:ffff888126139000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005587d939f950 CR3: 000000007c31a000 CR4: 00000000003526f0
----------------
Code disassembly (best guess), 1 bytes skipped:
0: ff c3 inc %ebx
2: 66 2e 0f 1f 84 00 00 cs nopw 0x0(%rax,%rax,1)
9: 00 00 00
c: 0f 1f 40 00 nopl 0x0(%rax)
10: 48 89 f8 mov %rdi,%rax
13: 48 89 f7 mov %rsi,%rdi
16: 48 89 d6 mov %rdx,%rsi
19: 48 89 ca mov %rcx,%rdx
1c: 4d 89 c2 mov %r8,%r10
1f: 4d 89 c8 mov %r9,%r8
22: 4c 8b 4c 24 08 mov 0x8(%rsp),%r9
27: 0f 05 syscall
* 29: 48 3d 01 f0 ff ff cmp $0xfffffffffffff001,%rax <-- trapping instruction
2f: 73 01 jae 0x32
31: c3 ret
32: 48 c7 c1 a8 ff ff ff mov $0xffffffffffffffa8,%rcx
39: f7 d8 neg %eax
3b: 64 89 01 mov %eax,%fs:(%rcx)
3e: 48 rex.W
Tested on:
commit: b3717b4d DO-NOT-MERGE: mptcp: enabled by default
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/matttbe/net-next.git b4/net-mptcp-clear-sched-rtx
console output: https://syzkaller.appspot.com/x/log.txt?x=1037ee92580000
kernel config: https://syzkaller.appspot.com/x/.config?x=14b6a9313e132a6b
dashboard link: https://syzkaller.appspot.com/bug?extid=3a92d359bc2ec6255a33
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
Note: no patches were applied.
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2025-11-26 12:33 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
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[not found] <5a35524e-68b4-4c6e-a0eb-cc7ca21b2d3a@kernel.org>
2025-11-26 11:51 ` [syzbot] [net?] divide error in __tcp_select_window (4) syzbot
[not found] <5e24b887-4eb3-474e-9560-fd0c0ffacb8e@kernel.org>
2025-11-26 12:33 ` syzbot
[not found] <914539f5-5e27-464e-a572-ada0a475d0f1@kernel.org>
2025-11-26 12:20 ` syzbot
2025-11-26 12:22 ` Matthieu Baerts
2025-11-25 19:50 syzbot
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