WARNING in em_cmp_match

Status: auto-obsoleted due to no activity on 2026/10/28 12:55
Reported-by: syzbot+7cd568ea0d8c6ada6cbe@syzkaller.appspotmail.com
First crash: 288d, last: 201d
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Bug presence (1)
Date Name Commit Repro Result
2026/10/28 upstream (ToT) 65ba8f34ec88 C Didn't crash
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 WARNING in em_cmp_match origin:lts-only -1 syz, C inconclusive 10 201d 286d 0/2 upstream: reported C repro on 2026/01/23 05:37

Sample crash report:
device syzkaller0 entered promiscuous mode
------------[ cut here ]------------
WARNING: CPU: 1 PID: 6280 at include/linux/skbuff.h:2876 skb_transport_header include/linux/skbuff.h:2876 [inline]
WARNING: CPU: 1 PID: 6280 at include/linux/skbuff.h:2876 tcf_get_base_ptr include/net/pkt_cls.h:529 [inline]
WARNING: CPU: 1 PID: 6280 at include/linux/skbuff.h:2876 em_cmp_match+0x56a/0x7b0 net/sched/em_cmp.c:25
Modules linked in:
CPU: 1 PID: 6280 Comm: syz.1.575 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:skb_transport_header include/linux/skbuff.h:2876 [inline]
RIP: 0010:tcf_get_base_ptr include/net/pkt_cls.h:529 [inline]
RIP: 0010:em_cmp_match+0x56a/0x7b0 net/sched/em_cmp.c:25
Code: e8 1b 41 1a f9 39 dd 0f 94 c0 e9 40 fe ff ff e8 ac 3f 1a f9 e9 34 fe ff ff e8 a2 3f 1a f9 0f 0b e9 97 fc ff ff e8 96 3f 1a f9 <0f> 0b e9 79 fb ff ff 89 d9 80 e1 07 fe c1 38 c1 0f 8c e5 fa ff ff
RSP: 0018:ffffc9000cbd7118 EFLAGS: 00010287
RAX: ffffffff886835ba RBX: ffff888026a88c2a RCX: 0000000000080000
RDX: ffffc9000c559000 RSI: 000000000000032d RDI: 000000000000032e
RBP: 000000000000ffff R08: ffff888079b61dc0 R09: 0000000000000003
R10: 0000000000000002 R11: 0000000000000002 R12: 1ffff11004d51185
R13: 1ffff1100afd3266 R14: ffff888057e99280 R15: ffff888057e99336
FS:  00007fb0357e56c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000027000 CR3: 0000000055e0c000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 tcf_em_match net/sched/ematch.c:494 [inline]
 __tcf_em_tree_match+0x1cb/0x7a0 net/sched/ematch.c:520
 tcf_em_tree_match include/net/pkt_cls.h:502 [inline]
 basic_classify+0x111/0x2c0 net/sched/cls_basic.c:48
 __tcf_classify net/sched/cls_api.c:1569 [inline]
 tcf_classify+0x331/0xbf0 net/sched/cls_api.c:1635
 multiq_classify net/sched/sch_multiq.c:39 [inline]
 multiq_enqueue+0xfb/0x4b0 net/sched/sch_multiq.c:66
 dev_qdisc_enqueue+0x4c/0x2b0 net/core/dev.c:3900
 __dev_xmit_skb net/core/dev.c:3989 [inline]
 __dev_queue_xmit+0xfdc/0x37c0 net/core/dev.c:4337
 packet_snd net/packet/af_packet.c:3127 [inline]
 packet_sendmsg+0x3bc3/0x4e60 net/packet/af_packet.c:3158
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 ____sys_sendmsg+0x5be/0x970 net/socket.c:2518
 ___sys_sendmsg+0x2a2/0x360 net/socket.c:2572
 __sys_sendmsg net/socket.c:2601 [inline]
 __do_sys_sendmsg net/socket.c:2610 [inline]
 __se_sys_sendmsg+0x1bb/0x2a0 net/socket.c:2608
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fb03499c819
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:00007fb0357e5028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fb034c15fa0 RCX: 00007fb03499c819
RDX: 000000000004c00c RSI: 00002000000000c0 RDI: 0000000000000005
RBP: 00007fb034a32c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb034c16038 R14: 00007fb034c15fa0 R15: 00007ffcb5fe1598
 </TASK>

Crashes (19):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/18 17:50 linux-6.1.y 7c87defbd336 303e2802 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in em_cmp_match
2026/03/24 23:22 linux-6.1.y f2ddafa93a25 74e70d19 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in em_cmp_match
2026/03/24 23:22 linux-6.1.y f2ddafa93a25 74e70d19 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in em_cmp_match
2026/03/01 14:05 linux-6.1.y 779f9571ac3e 43249bac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in em_cmp_match
2026/03/01 14:05 linux-6.1.y 779f9571ac3e 43249bac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in em_cmp_match
2026/02/23 00:37 linux-6.1.y 779f9571ac3e 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in em_cmp_match
2026/02/23 00:37 linux-6.1.y 779f9571ac3e 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in em_cmp_match
2026/02/22 13:54 linux-6.1.y 779f9571ac3e 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in em_cmp_match
2026/02/22 13:54 linux-6.1.y 779f9571ac3e 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in em_cmp_match
2026/02/19 00:29 linux-6.1.y 8ce36b2849ef 77d4d919 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in em_cmp_match
2026/02/18 21:08 linux-6.1.y 8ce36b2849ef 77d4d919 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in em_cmp_match
2026/01/22 04:24 linux-6.1.y cd9b81672742 8fc37797 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in em_cmp_match
2026/01/22 04:23 linux-6.1.y cd9b81672742 8fc37797 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in em_cmp_match
2026/04/18 16:05 linux-6.1.y 7c87defbd336 303e2802 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in em_cmp_match
2026/03/01 12:22 linux-6.1.y 779f9571ac3e 43249bac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in em_cmp_match
2026/03/01 12:22 linux-6.1.y 779f9571ac3e 43249bac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in em_cmp_match
2026/02/23 00:24 linux-6.1.y 779f9571ac3e 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in em_cmp_match
2026/01/22 03:30 linux-6.1.y cd9b81672742 8fc37797 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in em_cmp_match
2026/01/22 01:34 linux-6.1.y cd9b81672742 8fc37797 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in em_cmp_match
* Struck through repros no longer work on HEAD.