WARNING in u32_change

Status: upstream: reported C repro on 2026/02/22 20:25
Bug presence: origin:upstream
Labels: missing-backport
[Documentation on labels]
Reported-by: syzbot+b98f25656b791725fc13@syzkaller.appspotmail.com
First crash: 153d, last: 2d01h
Bug presence (3)
Date Name Commit Repro Result
2026/05/30 linux-6.6.y (ToT) 0a40c6fbd105 C [report] WARNING in u32_change
2026/02/23 upstream (ToT) 6de23f81a5e0 C [report] WARNING in u32_change
2026/05/30 upstream (ToT) 670b77dfebe7 C Didn't crash
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in u32_change (2) net -1 C error 760 101d 143d 29/29 fixed on 2026/05/21 07:50
upstream WARNING in u32_change net -1 C 28 1302d 1399d 22/29 fixed on 2023/02/24 13:50
linux-6.1 WARNING in u32_change -1 C 322 2d02h 153d 0/3 upstream: reported C repro on 2026/02/22 19:31
Fix bisection attempts (1)
Created Duration User Patch Repo Result
2026/06/18 00:29 2h26m fix candidate upstream OK (0) job log

Sample crash report:
netlink: 44 bytes leftover after parsing attributes in process `syz.0.17'.
------------[ cut here ]------------
memcpy: detected field-spanning write (size 32) of single field "&new->sel" at net/sched/cls_u32.c:855 (size 16)
WARNING: CPU: 1 PID: 5927 at net/sched/cls_u32.c:855 u32_init_knode net/sched/cls_u32.c:855 [inline]
WARNING: CPU: 1 PID: 5927 at net/sched/cls_u32.c:855 u32_change+0x1c5a/0x24f0 net/sched/cls_u32.c:921
Modules linked in:
CPU: 1 PID: 5927 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:u32_init_knode net/sched/cls_u32.c:855 [inline]
RIP: 0010:u32_change+0x1c5a/0x24f0 net/sched/cls_u32.c:921
Code: f8 eb 59 e8 78 00 d7 f8 c6 05 09 e0 c5 05 01 b9 10 00 00 00 48 c7 c7 c0 a3 c7 8b 4c 89 f6 48 c7 c2 40 a4 c7 8b e8 56 b2 a0 f8 <0f> 0b e9 86 f0 ff ff e8 4a 00 d7 f8 eb 24 e8 43 00 d7 f8 c6 05 a3
RSP: 0018:ffffc90004a5ed40 EFLAGS: 00010246
RAX: 6996ebfb5aee4500 RBX: ffff888030da8c00 RCX: ffff888022625a00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: ffffc90004a5eef8 R08: ffffc90004a5ea47 R09: 1ffff9200094bd48
R10: dffffc0000000000 R11: fffff5200094bd49 R12: ffff888031640c00
R13: ffff888031640ce8 R14: 0000000000000020 R15: ffff88807cec9dc0
FS:  0000555560a23500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000006040 CR3: 000000002c0c1000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 tc_new_tfilter+0x11f9/0x17c0 net/sched/cls_api.c:2354
 rtnetlink_rcv_msg+0x8b8/0xfa0 net/core/rtnetlink.c:6467
 netlink_rcv_skb+0x241/0x4d0 net/netlink/af_netlink.c:2545
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x5ba/0x960 net/socket.c:2594
 ___sys_sendmsg+0x2a6/0x360 net/socket.c:2648
 __sys_sendmmsg+0x2ca/0x510 net/socket.c:2734
 __do_sys_sendmmsg net/socket.c:2763 [inline]
 __se_sys_sendmmsg net/socket.c:2760 [inline]
 __x64_sys_sendmmsg+0xa0/0xb0 net/socket.c:2760
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f421f79ce59
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:00007ffe12056918 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f421fa15fa0 RCX: 00007f421f79ce59
RDX: 04000000000001f2 RSI: 0000200000000000 RDI: 0000000000000004
RBP: 00007f421f832d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f421fa15fac R14: 00007f421fa15fa0 R15: 00007f421fa15fa0
 </TASK>

Crashes (221):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/06/04 17:50 linux-6.6.y 924b4a879cbb 197909be .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/02/23 03:40 linux-6.6.y 7a137e9bfa0e 6e7b5511 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/02/23 02:21 linux-6.6.y 7a137e9bfa0e 6e7b5511 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/02/23 00:51 linux-6.6.y 7a137e9bfa0e 6e7b5511 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/02/22 23:30 linux-6.6.y 7a137e9bfa0e 6e7b5511 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/02/22 21:57 linux-6.6.y 7a137e9bfa0e 6e7b5511 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/07/23 19:05 linux-6.6.y da47cbc25466 71a13572 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/07/23 19:05 linux-6.6.y da47cbc25466 71a13572 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/07/21 06:47 linux-6.6.y da47cbc25466 de6a700d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/07/20 21:13 linux-6.6.y da47cbc25466 de6a700d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/07/18 14:37 linux-6.6.y da47cbc25466 72524a66 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/07/18 02:19 linux-6.6.y da47cbc25466 8aaff637 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/07/17 14:58 linux-6.6.y da47cbc25466 7f27c57a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/07/15 05:07 linux-6.6.y da47cbc25466 2130f682 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/07/14 19:46 linux-6.6.y da47cbc25466 2130f682 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/07/13 22:17 linux-6.6.y da47cbc25466 cc4833d0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/07/13 01:59 linux-6.6.y da47cbc25466 d78ea535 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/07/13 00:35 linux-6.6.y da47cbc25466 d78ea535 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/07/08 16:36 linux-6.6.y da47cbc25466 88a4b44c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/07/08 16:36 linux-6.6.y da47cbc25466 88a4b44c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/07/08 01:57 linux-6.6.y da47cbc25466 76cdc0c0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/07/07 06:49 linux-6.6.y da47cbc25466 8e71ce95 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/07/06 19:57 linux-6.6.y da47cbc25466 88b240e4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/07/06 09:59 linux-6.6.y da47cbc25466 fcece630 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/07/04 21:03 linux-6.6.y da47cbc25466 fcece630 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/07/04 09:12 linux-6.6.y d1cfde2d5d15 fcece630 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/07/04 06:16 linux-6.6.y d1cfde2d5d15 fcece630 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/07/03 12:12 linux-6.6.y d1cfde2d5d15 58bf2096 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/07/03 10:41 linux-6.6.y d1cfde2d5d15 58bf2096 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/07/02 23:51 linux-6.6.y d1cfde2d5d15 2b70b115 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/06/30 13:15 linux-6.6.y d1cfde2d5d15 fff8d0a0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/06/26 08:30 linux-6.6.y d1cfde2d5d15 7ff32d8b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/06/26 03:52 linux-6.6.y d1cfde2d5d15 7ff32d8b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/06/24 09:51 linux-6.6.y d1cfde2d5d15 042555ff .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/06/23 20:00 linux-6.6.y d1cfde2d5d15 4b1d8f01 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/06/16 20:46 linux-6.6.y 924b4a879cbb a3998659 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/06/14 02:52 linux-6.6.y 924b4a879cbb 1d2f3589 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/06/13 15:02 linux-6.6.y 924b4a879cbb 1d2f3589 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/06/13 05:30 linux-6.6.y 924b4a879cbb 1d2f3589 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/06/10 09:09 linux-6.6.y 924b4a879cbb 34dab4be .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/06/09 04:42 linux-6.6.y 924b4a879cbb 656e94c6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/06/09 01:13 linux-6.6.y 924b4a879cbb 656e94c6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/06/09 01:13 linux-6.6.y 924b4a879cbb 656e94c6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/06/08 03:30 linux-6.6.y 924b4a879cbb cc095639 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/06/07 02:38 linux-6.6.y 924b4a879cbb cc095639 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/06/05 07:29 linux-6.6.y 924b4a879cbb 197909be .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/06/05 02:36 linux-6.6.y 924b4a879cbb 197909be .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/06/04 18:53 linux-6.6.y 924b4a879cbb 197909be .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
2026/02/22 20:24 linux-6.6.y 7a137e9bfa0e 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in u32_change
* Struck through repros no longer work on HEAD.