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general protection fault in sigd_send

syzbot syzbot 1 participant 2 messages Oct 30, 2025 – Oct 31, 2025

Subsystems (3)
Networking Network drivers ATM
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syzbot

author syzbot
#0 lore raw

Hello,

syzbot found the following issue on:

HEAD commit:    84a905290cb4 net: phy: dp83867: Disable EEE support as not..
git tree:       net
console output: https://syzkaller.appspot.com/x/log.txt?x=113d2932580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=67b63a24f3c26fca
dashboard link: https://syzkaller.appspot.com/bug?extid=1f22cb1769f249df9fa0
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=119627e2580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16bc6f34580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/833b328a19a9/disk-84a90529.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1d97a2ab2baf/vmlinux-84a90529.xz
kernel image: https://storage.googleapis.com/syzbot-assets/cb504e793493/bzImage-84a90529.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:

Reported-by [email protected]
Oops: general protection fault, probably for non-canonical address 0xdffffc0000008034: 0000 [#1] SMP KASAN PTI
KASAN: probably user-memory-access in range [0x00000000000401a0-0x00000000000401a7]
CPU: 1 UID: 0 PID: 6129 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:sigd_send+0x48d/0xf90 net/atm/signaling.c:78
Code: 8d 67 14 4c 89 e0 48 c1 e8 03 0f b6 04 18 84 c0 0f 85 91 07 00 00 31 ed 41 2b 2c 24 49 8d be 9c 01 00 00 48 89 f8 48 c1 e8 03 <0f> b6 04 18 84 c0 0f 85 8f 07 00 00 41 89 ae 9c 01 00 00 49 8d be
RSP: 0018:ffffc90003737820 EFLAGS: 00010202
RAX: 0000000000008034 RBX: dffffc0000000000 RCX: 0000000000000005
RDX: ffffffff8a75f9af RSI: ffffffff8f4cf240 RDI: 00000000000401a0
RBP: 0000000000000000 R08: ffff88802cf50000 R09: 0000000000000007
R10: 000000000000000f R11: 0000000000000000 R12: ffff888058c8ea54
R13: 1ffff1100b191d48 R14: 0000000000040004 R15: ffff888058c8ea40
FS:  00007f9e83ba46c0(0000) GS:ffff88812623e000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f91aa192e9c CR3: 000000003195e000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 vcc_sendmsg+0xb2e/0xd70 net/atm/common.c:650
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:742
 ____sys_sendmsg+0x505/0x830 net/socket.c:2630
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2684
 __sys_sendmsg net/socket.c:2716 [inline]
 __do_sys_sendmsg net/socket.c:2721 [inline]
 __se_sys_sendmsg net/socket.c:2719 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2719
 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: 0033:0x7f9e82d8efc9
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:00007f9e83ba4038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f9e82fe5fa0 RCX: 00007f9e82d8efc9
RDX: 0000000000000000 RSI: 0000200000000500 RDI: 0000000000000004
RBP: 00007f9e82e11f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9e82fe6038 R14: 00007f9e82fe5fa0 R15: 00007fffa761f4e8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:sigd_send+0x48d/0xf90 net/atm/signaling.c:78
Code: 8d 67 14 4c 89 e0 48 c1 e8 03 0f b6 04 18 84 c0 0f 85 91 07 00 00 31 ed 41 2b 2c 24 49 8d be 9c 01 00 00 48 89 f8 48 c1 e8 03 <0f> b6 04 18 84 c0 0f 85 8f 07 00 00 41 89 ae 9c 01 00 00 49 8d be
RSP: 0018:ffffc90003737820 EFLAGS: 00010202
RAX: 0000000000008034 RBX: dffffc0000000000 RCX: 0000000000000005
RDX: ffffffff8a75f9af RSI: ffffffff8f4cf240 RDI: 00000000000401a0
RBP: 0000000000000000 R08: ffff88802cf50000 R09: 0000000000000007
R10: 000000000000000f R11: 0000000000000000 R12: ffff888058c8ea54
R13: 1ffff1100b191d48 R14: 0000000000040004 R15: ffff888058c8ea40
FS:  00007f9e83ba46c0(0000) GS:ffff88812623e000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f91aa192e9c CR3: 000000003195e000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
   0:	8d 67 14             	lea    0x14(%rdi),%esp
   3:	4c 89 e0             	mov    %r12,%rax
   6:	48 c1 e8 03          	shr    $0x3,%rax
   a:	0f b6 04 18          	movzbl (%rax,%rbx,1),%eax
   e:	84 c0                	test   %al,%al
  10:	0f 85 91 07 00 00    	jne    0x7a7
  16:	31 ed                	xor    %ebp,%ebp
  18:	41 2b 2c 24          	sub    (%r12),%ebp
  1c:	49 8d be 9c 01 00 00 	lea    0x19c(%r14),%rdi
  23:	48 89 f8             	mov    %rdi,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	0f b6 04 18          	movzbl (%rax,%rbx,1),%eax <-- trapping instruction
  2e:	84 c0                	test   %al,%al
  30:	0f 85 8f 07 00 00    	jne    0x7c5
  36:	41 89 ae 9c 01 00 00 	mov    %ebp,0x19c(%r14)
  3d:	49                   	rex.WB
  3e:	8d                   	.byte 0x8d
  3f:	be                   	.byte 0xbe

---
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author syzbot
#1 lore raw

Forwarded: general protection fault in sigd_send

For archival purposes, forwarding an incoming command email to [email protected].

For archival purposes, forwarding an incoming command email to [email protected].

***

Subject: general protection fault in sigd_send
Author: [email protected]

#syz test

---
 net/atm/signaling.c | 5 +++++
 1 file changed, 5 insertions(+)
net/atm/signaling.c +5 -0
index e70ae2c113f9..0fda16975c70 100644
@@ -63,6 +63,11 @@ static void modify_qos(struct atm_vcc *vcc, struct atmsvc_msg *msg)
 
 static int sigd_send(struct atm_vcc *vcc, struct sk_buff *skb)
 {
+	if (vcc != sigd || !test_bit(ATM_VF_SESSION, &vcc->flags)) {
+		dev_kfree_skb(skb);
+		return -EPERM;
+	}
+
 	struct atmsvc_msg *msg;
 	struct atm_vcc *session_vcc;
 	struct sock *sk;
Signature · 1 line
2.43.0