------------[ cut here ]------------
!skb_shinfo(skb)->nr_frags
WARNING: net/kcm/kcmsock.c:631 at kcm_write_msgs+0x1452/0x1610 net/kcm/kcmsock.c:631, CPU#1: syz.4.2942/21557
Modules linked in:
CPU: 1 UID: 0 PID: 21557 Comm: syz.4.2942 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
RIP: 0010:kcm_write_msgs+0x1452/0x1610 net/kcm/kcmsock.c:631
Code: f8 f8 f8 c6 44 18 10 f8 eb 68 e8 a9 fc fa f6 e9 56 ed ff ff e8 9f fc fa f6 45 31 e4 45 31 ed e9 46 ed ff ff e8 8f fc fa f6 90 <0f> 0b 90 41 bc ea ff ff ff 48 bb 00 00 00 00 00 fc ff df eb a8 e8
RSP: 0018:ffffc9000bb27720 EFLAGS: 00010293
RAX: ffffffff8ac94691 RBX: 0000000000000180 RCX: ffff88802d933c80
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000bb278f0 R08: ffffc9000bb27867 R09: ffffc9000bb27800
R10: dffffc0000000000 R11: fffff52001764f0d R12: dffffc0000000000
R13: ffff888038924b00 R14: ffff88807ae61040 R15: 0000000000000000
FS:  00007fefa311e6c0(0000) GS:ffff8881255a0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f80493e6ad8 CR3: 00000000ad67f000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 kcm_sendmsg+0x24bc/0x2b00 net/kcm/kcmsock.c:907
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 sock_write_iter+0x503/0x550 net/socket.c:1195
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x61d/0xb90 fs/read_write.c:688
 ksys_write+0x150/0x270 fs/read_write.c:740
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fefa219bf79
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:00007fefa311e028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fefa2416090 RCX: 00007fefa219bf79
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 00007fefa22327e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fefa2416128 R14: 00007fefa2416090 R15: 00007ffc01f2db38
 </TASK>