syzbot


general protection fault in ife_tlv_meta_encode

Status: upstream: reported C repro on 2026/01/21 13:35
Subsystems: net
[Documentation on labels]
Reported-by: syzbot+5cf914f193dffde3bd3c@syzkaller.appspotmail.com
Fix commit: 27880b0b0d35 net/sched: act_ife: avoid possible NULL deref
Patched on: [ci-qemu-gce-upstream-auto ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-snapshot-upstream-root ci-upstream-bpf-kasan-gce ci-upstream-gce-leak ci-upstream-kasan-badwrites-root ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-kmsan-gce-386-root ci-upstream-kmsan-gce-root ci-upstream-linux-next-kasan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci-upstream-rust-kasan-gce ci2-upstream-fs ci2-upstream-kcsan-gce], missing on: [ci-qemu-native-arm64-kvm ci-qemu2-riscv64 ci-upstream-bpf-next-kasan-gce ci-upstream-gce-arm64 ci2-upstream-usb]
First crash: 2d22h, last: 2d02h
Cause bisection: failed (error log, bisect log)
  
Discussions (2)
Title Replies (including bot) Last reply
[PATCH net] net/sched: act_ife: avoid possible NULL deref 3 (3) 2026/01/22 16:10
[syzbot] [net?] general protection fault in ife_tlv_meta_encode 0 (2) 2026/01/22 03:47

Sample crash report:
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 UID: 0 PID: 5470 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:ife_tlv_meta_encode+0x46/0xb0 net/ife/ife.c:166
Code: 70 87 71 f6 45 8d 77 07 4d 8d 65 04 c1 e5 10 44 89 fb 83 c3 04 09 eb 0f cb 4c 89 e8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <0f> b6 04 08 84 c0 75 43 41 89 5d 00 41 81 e6 fc ff 00 00 41 8d 46
RSP: 0018:ffffc90003a1ef60 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000008000300 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000000
RBP: 0000000000030000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff897bb640 R12: 0000000000000004
R13: 0000000000000000 R14: 000000000000000b R15: 0000000000000004
FS:  000055555b1ae500(0000) GS:ffff88808cf1d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fcb54861de0 CR3: 00000000343e7000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 ife_encode_meta_u32+0x126/0x1c0 net/sched/act_ife.c:101
 tcf_ife_encode net/sched/act_ife.c:841 [inline]
 tcf_ife_act+0x10fd/0x1d80 net/sched/act_ife.c:877
 tc_act include/net/tc_wrapper.h:130 [inline]
 tcf_action_exec+0x185/0x8e0 net/sched/act_api.c:1152
 tc_classify include/net/tc_wrapper.h:197 [inline]
 __tcf_classify net/sched/cls_api.c:1764 [inline]
 tcf_classify+0x4cf/0x1130 net/sched/cls_api.c:1860
 multiq_classify net/sched/sch_multiq.c:39 [inline]
 multiq_enqueue+0x102/0x4d0 net/sched/sch_multiq.c:66
 dev_qdisc_enqueue+0x4e/0x240 net/core/dev.c:4147
 __dev_xmit_skb net/core/dev.c:4262 [inline]
 __dev_queue_xmit+0x1933/0x32b0 net/core/dev.c:4798
 packet_snd net/packet/af_packet.c:3076 [inline]
 packet_sendmsg+0x3eb6/0x50f0 net/packet/af_packet.c:3108
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:742
 ____sys_sendmsg+0x4d7/0x810 net/socket.c:2592
 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2646
 __sys_sendmsg net/socket.c:2678 [inline]
 __do_sys_sendmsg net/socket.c:2683 [inline]
 __se_sys_sendmsg net/socket.c:2681 [inline]
 __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2681
 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: 0033:0x7f54ee59acb9
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:00007ffc012e66e8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f54ee815fa0 RCX: 00007f54ee59acb9
RDX: 0000000000000004 RSI: 00002000000000c0 RDI: 0000000000000008
RBP: 00007ffc012e6750 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007f54ee815fac R14: 00007f54ee815fa0 R15: 00007f54ee815fa0
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ife_tlv_meta_encode+0x46/0xb0 net/ife/ife.c:166
Code: 70 87 71 f6 45 8d 77 07 4d 8d 65 04 c1 e5 10 44 89 fb 83 c3 04 09 eb 0f cb 4c 89 e8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <0f> b6 04 08 84 c0 75 43 41 89 5d 00 41 81 e6 fc ff 00 00 41 8d 46
RSP: 0018:ffffc90003a1ef60 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000008000300 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000000
RBP: 0000000000030000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff897bb640 R12: 0000000000000004
R13: 0000000000000000 R14: 000000000000000b R15: 0000000000000004
FS:  000055555b1ae500(0000) GS:ffff88808cf1d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fcb54861de0 CR3: 00000000343e7000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess):
   0:	70 87                	jo     0xffffff89
   2:	71 f6                	jno    0xfffffffa
   4:	45 8d 77 07          	lea    0x7(%r15),%r14d
   8:	4d 8d 65 04          	lea    0x4(%r13),%r12
   c:	c1 e5 10             	shl    $0x10,%ebp
   f:	44 89 fb             	mov    %r15d,%ebx
  12:	83 c3 04             	add    $0x4,%ebx
  15:	09 eb                	or     %ebp,%ebx
  17:	0f cb                	bswap  %ebx
  19:	4c 89 e8             	mov    %r13,%rax
  1c:	48 c1 e8 03          	shr    $0x3,%rax
  20:	48 b9 00 00 00 00 00 	movabs $0xdffffc0000000000,%rcx
  27:	fc ff df
* 2a:	0f b6 04 08          	movzbl (%rax,%rcx,1),%eax <-- trapping instruction
  2e:	84 c0                	test   %al,%al
  30:	75 43                	jne    0x75
  32:	41 89 5d 00          	mov    %ebx,0x0(%r13)
  36:	41 81 e6 fc ff 00 00 	and    $0xfffc,%r14d
  3d:	41                   	rex.B
  3e:	8d                   	.byte 0x8d
  3f:	46                   	rex.RX

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/22 03:54 upstream cf38b2340c0e 8fc37797 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root general protection fault in ife_tlv_meta_encode
2026/01/22 03:47 net-next d8f87aa5fa0a 101dad69 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce general protection fault in ife_tlv_meta_encode
2026/01/21 18:42 upstream 6c790212c588 6f1aa2f9 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 general protection fault in ife_tlv_meta_encode
2026/01/22 02:38 upstream cf38b2340c0e 8fc37797 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root general protection fault in ife_tlv_meta_encode
2026/01/21 07:54 upstream c03e9c42ae8f d1b870e1 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 general protection fault in ife_tlv_meta_encode
2026/01/22 02:36 net-next d8f87aa5fa0a 101dad69 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce general protection fault in ife_tlv_meta_encode
* Struck through repros no longer work on HEAD.