syzbot


general protection fault in ax25_output

Status: moderation: reported on 2026/01/26 21:05
Subsystems: hams
[Documentation on labels]
Reported-by: syzbot+a33553d7dbe140fc9e3e@syzkaller.appspotmail.com
First crash: 3d19h, last: 3d19h

Sample crash report:
Oops: general protection fault, probably for non-canonical address 0xdffffc000000000c: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000060-0x0000000000000067]
CPU: 1 UID: 0 PID: 17885 Comm: syz.3.11630 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/13/2026
RIP: 0010:ax25_output+0x899/0xa20 net/ax25/ax25_out.c:199
Code: 4b dd fe 49 8d 5f 28 48 89 d8 48 c1 e8 03 80 3c 28 00 74 08 48 89 df e8 d5 3a a8 f7 48 8b 1b 4c 8d 73 60 4c 89 f0 48 c1 e8 03 <0f> b6 04 28 84 c0 0f 85 e5 00 00 00 45 8b 36 4c 89 f7 48 c7 c6 90
RSP: 0018:ffffc900107df918 EFLAGS: 00010206
RAX: 000000000000000c RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000006 RSI: ffffffff8dccefc3 RDI: 00000000ffffffff
RBP: dffffc0000000000 R08: ffffffff8fef0f77 R09: 1ffffffff1fde1ee
R10: dffffc0000000000 R11: fffffbfff1fde1ef R12: ffff88805d53a6b0
R13: ffff88805d53a640 R14: 0000000000000060 R15: ffff8880739bc000
FS:  00007f2552a8e6c0(0000) GS:ffff8881257f3000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c30520d CR3: 0000000035342000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 ax25_send_frame+0x310/0x9f0 net/ax25/ax25_out.c:-1
 rose_send_frame net/rose/rose_link.c:106 [inline]
 rose_transmit_restart_request net/rose/rose_link.c:198 [inline]
 rose_transmit_link+0x729/0xac0 net/rose/rose_link.c:284
 rose_write_internal+0x1256/0x1b60 net/rose/rose_subr.c:198
 rose_connect+0x93b/0x1110 net/rose/af_rose.c:881
 __sys_connect_file net/socket.c:2089 [inline]
 __sys_connect+0x312/0x450 net/socket.c:2108
 __do_sys_connect net/socket.c:2114 [inline]
 __se_sys_connect net/socket.c:2111 [inline]
 __x64_sys_connect+0x7a/0x90 net/socket.c:2111
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2551b9aeb9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2552a8e028 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007f2551e16090 RCX: 00007f2551b9aeb9
RDX: 0000000000000040 RSI: 0000200000000100 RDI: 000000000000000e
RBP: 00007f2551c08c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2551e16128 R14: 00007f2551e16090 R15: 00007ffd610ffd08
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ax25_output+0x899/0xa20 net/ax25/ax25_out.c:199
Code: 4b dd fe 49 8d 5f 28 48 89 d8 48 c1 e8 03 80 3c 28 00 74 08 48 89 df e8 d5 3a a8 f7 48 8b 1b 4c 8d 73 60 4c 89 f0 48 c1 e8 03 <0f> b6 04 28 84 c0 0f 85 e5 00 00 00 45 8b 36 4c 89 f7 48 c7 c6 90
RSP: 0018:ffffc900107df918 EFLAGS: 00010206
RAX: 000000000000000c RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000006 RSI: ffffffff8dccefc3 RDI: 00000000ffffffff
RBP: dffffc0000000000 R08: ffffffff8fef0f77 R09: 1ffffffff1fde1ee
R10: dffffc0000000000 R11: fffffbfff1fde1ef R12: ffff88805d53a6b0
R13: ffff88805d53a640 R14: 0000000000000060 R15: ffff8880739bc000
FS:  00007f2552a8e6c0(0000) GS:ffff8881256f3000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2551be8600 CR3: 0000000035342000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
   0:	4b dd fe             	rex.WXB (bad)
   3:	49 8d 5f 28          	lea    0x28(%r15),%rbx
   7:	48 89 d8             	mov    %rbx,%rax
   a:	48 c1 e8 03          	shr    $0x3,%rax
   e:	80 3c 28 00          	cmpb   $0x0,(%rax,%rbp,1)
  12:	74 08                	je     0x1c
  14:	48 89 df             	mov    %rbx,%rdi
  17:	e8 d5 3a a8 f7       	call   0xf7a83af1
  1c:	48 8b 1b             	mov    (%rbx),%rbx
  1f:	4c 8d 73 60          	lea    0x60(%rbx),%r14
  23:	4c 89 f0             	mov    %r14,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	0f b6 04 28          	movzbl (%rax,%rbp,1),%eax <-- trapping instruction
  2e:	84 c0                	test   %al,%al
  30:	0f 85 e5 00 00 00    	jne    0x11b
  36:	45 8b 36             	mov    (%r14),%r14d
  39:	4c 89 f7             	mov    %r14,%rdi
  3c:	48                   	rex.W
  3d:	c7                   	.byte 0xc7
  3e:	c6                   	(bad)
  3f:	90                   	nop

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/26 19:27 net-next bf2e36c9dab9 a4c52dd6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce general protection fault in ax25_output
* Struck through repros no longer work on HEAD.