syzbot


general protection fault in nexthop_get_nhc_lookup

Status: premoderation: reported on 2025/08/09 17:13
Reported-by: syzbot+09f8afade471d844a5b6@syzkaller.appspotmail.com
First crash: 20d, last: 9d13h
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-10 general protection fault in nexthop_get_nhc_lookup 2 9 11d 50d 0/2 premoderation: reported on 2025/07/09 23:30

Sample crash report:
general protection fault, probably for non-canonical address 0xdffffc000000005a: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x00000000000002d0-0x00000000000002d7]
CPU: 0 PID: 28854 Comm: syz.5.7972 Not tainted 6.1.145-syzkaller-00015-g87b9d836c3d8 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:ip_ignore_linkdown include/linux/inetdevice.h:259 [inline]
RIP: 0010:fib_lookup_good_nhc net/ipv4/fib_trie.c:1413 [inline]
RIP: 0010:nexthop_get_nhc_lookup+0x17e/0x750 include/net/nexthop.h:405
Code: d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 68 4a 7c fd 48 89 5d a8 48 8b 1b b8 d0 02 00 00 48 01 c3 48 89 d8 48 c1 e8 03 <42> 80 3c 28 00 74 08 48 89 df e8 43 4a 7c fd 48 8b 1b 48 85 db 0f
RSP: 0018:ffffc900099fef50 EFLAGS: 00010206
RAX: 000000000000005a RBX: 00000000000002d0 RCX: 0000000000000002
RDX: ffff888126028000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900099fefc0 R08: dffffc0000000000 R09: ffffc900099ff190
R10: fffff5200133fe3a R11: 1ffff9200133fe32 R12: ffff88811be07c00
R13: dffffc0000000000 R14: 0000000000000000 R15: ffffc900099ff190
FS:  00007f49307f76c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffffd CR3: 000000011a9b5000 CR4: 00000000003506b0
Call Trace:
 <TASK>
 fib_table_lookup+0x10b7/0x1a60 net/ipv4/fib_trie.c:1590
 nl_fib_lookup net/ipv4/fib_frontend.c:1374 [inline]
 nl_fib_input+0x477/0x840 net/ipv4/fib_frontend.c:1408
 netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline]
 netlink_unicast+0x8b1/0xa30 net/netlink/af_netlink.c:1338
 netlink_sendmsg+0x8aa/0xbc0 net/netlink/af_netlink.c:1860
 sock_sendmsg_nosec net/socket.c:716 [inline]
 __sock_sendmsg net/socket.c:728 [inline]
 sock_sendmsg net/socket.c:751 [inline]
 kernel_sendmsg+0x222/0x320 net/socket.c:775
 sock_no_sendpage+0xf4/0x150 net/core/sock.c:3258
 kernel_sendpage+0x256/0x2d0 net/socket.c:3596
 sock_sendpage+0x86/0xb0 net/socket.c:1079
 pipe_to_sendpage+0x22d/0x320 fs/splice.c:360
 splice_from_pipe_feed fs/splice.c:414 [inline]
 __splice_from_pipe+0x33b/0x910 fs/splice.c:558
 splice_from_pipe fs/splice.c:593 [inline]
 generic_splice_sendpage+0xf3/0x150 fs/splice.c:742
 do_splice_from fs/splice.c:763 [inline]
 direct_splice_actor+0xf7/0x130 fs/splice.c:930
 splice_direct_to_actor+0x4a2/0xb10 fs/splice.c:885
 do_splice_direct+0x1b3/0x2c0 fs/splice.c:973
 do_sendfile+0x5c6/0xeb0 fs/read_write.c:1255
 __do_sys_sendfile64 fs/read_write.c:1323 [inline]
 __se_sys_sendfile64 fs/read_write.c:1309 [inline]
 __x64_sys_sendfile64+0x18f/0x1f0 fs/read_write.c:1309
 x64_sys_call+0x62c/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f4931d8ebe9
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:00007f49307f7038 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f4931fb5fa0 RCX: 00007f4931d8ebe9
RDX: 0000000000000000 RSI: 0000000000000005 RDI: 0000000000000004
RBP: 00007f4931e11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 000080001d00c0d1 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4931fb6038 R14: 00007f4931fb5fa0 R15: 00007ffed9dd17b8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ip_ignore_linkdown include/linux/inetdevice.h:259 [inline]
RIP: 0010:fib_lookup_good_nhc net/ipv4/fib_trie.c:1413 [inline]
RIP: 0010:nexthop_get_nhc_lookup+0x17e/0x750 include/net/nexthop.h:405
Code: d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 68 4a 7c fd 48 89 5d a8 48 8b 1b b8 d0 02 00 00 48 01 c3 48 89 d8 48 c1 e8 03 <42> 80 3c 28 00 74 08 48 89 df e8 43 4a 7c fd 48 8b 1b 48 85 db 0f
RSP: 0018:ffffc900099fef50 EFLAGS: 00010206
RAX: 000000000000005a RBX: 00000000000002d0 RCX: 0000000000000002
RDX: ffff888126028000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900099fefc0 R08: dffffc0000000000 R09: ffffc900099ff190
R10: fffff5200133fe3a R11: 1ffff9200133fe32 R12: ffff88811be07c00
R13: dffffc0000000000 R14: 0000000000000000 R15: ffffc900099ff190
FS:  00007f49307f76c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffffd CR3: 000000011a9b5000 CR4: 00000000003506b0
----------------
Code disassembly (best guess):
   0:	d8 48 c1             	fmuls  -0x3f(%rax)
   3:	e8 03 42 80 3c       	call   0x3c80420b
   8:	28 00                	sub    %al,(%rax)
   a:	74 08                	je     0x14
   c:	48 89 df             	mov    %rbx,%rdi
   f:	e8 68 4a 7c fd       	call   0xfd7c4a7c
  14:	48 89 5d a8          	mov    %rbx,-0x58(%rbp)
  18:	48 8b 1b             	mov    (%rbx),%rbx
  1b:	b8 d0 02 00 00       	mov    $0x2d0,%eax
  20:	48 01 c3             	add    %rax,%rbx
  23:	48 89 d8             	mov    %rbx,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 80 3c 28 00       	cmpb   $0x0,(%rax,%r13,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	48 89 df             	mov    %rbx,%rdi
  34:	e8 43 4a 7c fd       	call   0xfd7c4a7c
  39:	48 8b 1b             	mov    (%rbx),%rbx
  3c:	48 85 db             	test   %rbx,%rbx
  3f:	0f                   	.byte 0xf

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/20 05:06 android14-6.1 87b9d836c3d8 79512909 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 general protection fault in nexthop_get_nhc_lookup
2025/08/20 05:05 android14-6.1 87b9d836c3d8 79512909 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 general protection fault in nexthop_get_nhc_lookup
2025/08/20 04:40 android14-6.1 87b9d836c3d8 79512909 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 general protection fault in nexthop_get_nhc_lookup
2025/08/14 10:29 android14-6.1 c750dc582629 22ec1469 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 general protection fault in nexthop_get_nhc_lookup
2025/08/10 18:29 android14-6.1 c750dc582629 32a0e5ed .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 general protection fault in nexthop_get_nhc_lookup
2025/08/10 07:01 android14-6.1 c750dc582629 32a0e5ed .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 general protection fault in nexthop_get_nhc_lookup
2025/08/09 17:12 android14-6.1 c750dc582629 32a0e5ed .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 general protection fault in nexthop_get_nhc_lookup
* Struck through repros no longer work on HEAD.