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Message-ID:
<SY8P300MB04214534155F05358161B402A1D92@SY8P300MB0421.AUSP300.PROD.OUTLOOK.COM>
Date: Wed, 19 Mar 2025 08:26:20 +0000
From: YAN KANG <kangyan91@...look.com>
To: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
<pabeni@...hat.com>, Simon Horman <horms@...nel.org>, Simon Horman
<horms@...nel.org>, "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: general protection fault in llc_conn_state_process
Dear maintainers,
I found a new kernel bug titiled "general protection fault in llc_conn_state_process" while using modified syzkaller fuzzing tool. I tested it on the Linux upstream version (6.13.0-rc7) . Although I don't have repro, the crash log is sufficient to describe the cause of the bug.
RootCause Analysis:
function llc_conn_state_process in /net/llc/llc_conn.c
case LLC_CONN_PRIM:
if (sk->sk_type == SOCK_STREAM &&
sk->sk_state == TCP_SYN_SENT) {
if (ev->status) {
sk->sk_socket->state = SS_UNCONNECTED; //crash, sk->sk_socket == NULL
sk->sk_state = TCP_CLOSE;
} else {
sk->sk_socket->state = SS_CONNECTED;
sk->sk_state = TCP_ESTABLISHED;
}
sk->sk_state_change(sk);
}
break;
Bug occurs:
Thread A Thread B
---------------------- ----------------------
call_timer_fn sock_close
- llc_conn_tmr_common_cb - llc_ui_release
- llc_process_tmr_ev |- lock_sock
-llc_conn_state_process |- release_sock
| |-sock_orphan(sk)
| |-sk_set_socket(sk, NULL); [1]
case LLC_CONN_PRIM:
sk->sk_socket->state = SS_UNCONNECTED; [2] crash ,NPD!!
Fix Suggestion:
Using lock_sock & release_sock in case LLC_CONN_PRIM and putting sock_orphan in lock windows.
BTW: in case LLC_CONN_PRIM , Is it necessary to add sock_hold and sock_put?
If you fix this issue, please add the following tag to the commit:
Reported-by: yan kang <kangyan91@...look.com>
Reported-by: yue sun <samsun1006219@...il.com>
I hope it helps.
Best regards
yan kang
Kernel crash log is below.
==================================================================
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 UID: 0 PID: 27544 Comm: syz.7.2138 Not tainted 6.13.0-rc7-00006-g7122647c49bb-dirty #112
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
RIP: 0010:llc_conn_state_process+0x9f0/0x1870 net/llc/llc_conn.c:141
Code: 8b 98 b0 01 00 00 e8 0f f1 79 f8 40 84 ed 0f 84 b0 0b 00 00 e8 71 fb 79 f8 48 89 da 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 6a 0d 00 00 48 8b 44 24 08 c7
RSP: 0018:ffffc900001e8ca0 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff891f2831
RDX: 0000000000000000 RSI: ffffffff891f283f RDI: 0000000000000001
RBP: 0000000000000002 R08: 0000000000000001 R09: ffffed1024df062a
R10: 0000000000000002 R11: 0000000000000000 R12: ffff888121e90600
R13: 0000000000000000 R14: dffffc0000000000 R15: ffff888126f83000
FS: 0000000000000000(0000) GS:ffff888135e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c4052be CR3: 000000004f53a000 CR4: 0000000000752ef0
PKRU: 80000008
Call Trace:
<IRQ>
llc_process_tmr_ev net/llc/llc_c_ac.c:1445 [inline]
llc_conn_tmr_common_cb+0x44e/0x8e0 net/llc/llc_c_ac.c:1331
call_timer_fn+0x1a6/0x620 kernel/time/timer.c:1793
expire_timers kernel/time/timer.c:1844 [inline]
__run_timers+0x659/0x8f0 kernel/time/timer.c:2418
__run_timer_base kernel/time/timer.c:2430 [inline]
__run_timer_base kernel/time/timer.c:2422 [inline]
run_timer_base+0xc5/0x120 kernel/time/timer.c:2439
run_timer_softirq+0x1a/0x40 kernel/time/timer.c:2449
handle_softirqs+0x1bf/0x850 kernel/softirq.c:561
do_softirq kernel/softirq.c:462 [inline]
do_softirq+0xac/0xe0 kernel/softirq.c:449
</IRQ>
<TASK>
__local_bh_enable_ip+0x100/0x120 kernel/softirq.c:389
sock_orphan include/net/sock.h:2029 [inline]
llc_ui_release+0x411/0x8f0 net/llc/af_llc.c:229
__sock_release+0xb0/0x270 net/socket.c:640
sock_close+0x1c/0x30 net/socket.c:1408
__fput+0x3f8/0xb40 fs/file_table.c:450
task_work_run+0x169/0x260 kernel/task_work.c:239
exit_task_work include/linux/task_work.h:43 [inline]
do_exit+0xacc/0x2ce0 kernel/exit.c:938
do_group_exit+0xd3/0x2a0 kernel/exit.c:1087
get_signal+0x222c/0x2500 kernel/signal.c:3017
arch_do_signal_or_restart+0x81/0x7d0 arch/x86/kernel/signal.c:337
exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0x150/0x2a0 kernel/entry/common.c:218
do_syscall_64+0xd8/0x250 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f189f5a6a2d
Code: Unable to access opcode bytes at 0x7f189f5a6a03.
RSP: 002b:00007f18a0330f98 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: fffffffffffffe00 RBX: 00007f189f7b5fa0 RCX: 00007f189f5a6a2d
RDX: 0000000000000010 RSI: 0000000020000000 RDI: 0000000000000006
RBP: 00007f189f639f8e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f189f7b5fac R14: 00007f189f7b5fa0 R15: 00007f18a0311000
</TASK>
Modules linked in:
hpet: Lost 3 RTC interrupts
---[ end trace 0000000000000000 ]---
RIP: 0010:llc_conn_state_process+0x9f0/0x1870 net/llc/llc_conn.c:141
Code: 8b 98 b0 01 00 00 e8 0f f1 79 f8 40 84 ed 0f 84 b0 0b 00 00 e8 71 fb 79 f8 48 89 da 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 6a 0d 00 00 48 8b 44 24 08 c7
RSP: 0018:ffffc900001e8ca0 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff891f2831
RDX: 0000000000000000 RSI: ffffffff891f283f RDI: 0000000000000001
RBP: 0000000000000002 R08: 0000000000000001 R09: ffffed1024df062a
R10: 0000000000000002 R11: 0000000000000000 R12: ffff888121e90600
R13: 0000000000000000 R14: dffffc0000000000 R15: ffff888126f83000
FS: 0000000000000000(0000) GS:ffff888135e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c4052be CR3: 000000004f53a000 CR4: 0000000000752ef0
PKRU: 80000008
----------------
Code disassembly (best guess):
0: 8b 98 b0 01 00 00 mov 0x1b0(%rax),%ebx
6: e8 0f f1 79 f8 call 0xf879f11a
b: 40 84 ed test %bpl,%bpl
e: 0f 84 b0 0b 00 00 je 0xbc4
14: e8 71 fb 79 f8 call 0xf879fb8a
19: 48 89 da mov %rbx,%rdx
1c: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
23: fc ff df
26: 48 c1 ea 03 shr $0x3,%rdx
* 2a: 0f b6 04 02 movzbl (%rdx,%rax,1),%eax <-- trapping instruction
2e: 84 c0 test %al,%al
30: 74 08 je 0x3a
32: 3c 03 cmp $0x3,%al
34: 0f 8e 6a 0d 00 00 jle 0xda4
3a: 48 8b 44 24 08 mov 0x8(%rsp),%rax
3f: c7 .byte 0xc7
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