WARNING in smb2_add_credits

Status: upstream: reported syz repro on 2026/07/28 12:45
Reported-by: syzbot+04d6a0157da850d58691@syzkaller.appspotmail.com
First crash: 53d, last: 25m
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in smb2_add_credits prio:high cifs -1 syz, C unreliable 700 46m 49d 0/29 upstream: reported C repro on 2026/08/01 00:35
linux-5.15 WARNING in smb2_add_credits origin:upstream -1 syz, C 14 5d07h 40d 0/3 upstream: reported C repro on 2026/08/10 08:53

Sample crash report:
CIFS: VFS: \\127.0.0.1 Error -104 sending data on socket to server
------------[ cut here ]------------
WARNING: CPU: 0 PID: 6880 at fs/smb/client/smb2ops.c:97 smb2_add_credits+0x1365/0x2600 fs/smb/client/smb2ops.c:97
Modules linked in:
CPU: 0 PID: 6880 Comm: syz.0.197 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:smb2_add_credits+0x1365/0x2600 fs/smb/client/smb2ops.c:97
Code: 03 42 80 3c 28 00 74 08 4c 89 e7 e8 75 91 3c ff 49 8b 34 24 48 c7 c7 e0 23 f7 8a e8 75 3d e2 07 e9 eb f9 ff ff e8 3b 05 e4 fe <0f> 0b e9 d9 ef ff ff e8 2f 05 e4 fe c6 05 f8 2c d3 0b 01 48 c7 c7
RSP: 0018:ffffc9000bd6f400 EFLAGS: 00010293
RAX: ffffffff82a38615 RBX: ffff88802d66e2c0 RCX: ffff88801e2a3c00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000200 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff520017ade70 R12: 1ffff11005acdc58
R13: dffffc0000000000 R14: ffff88802d66e000 R15: 0000000000000000
FS:  00007f08586ae6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002e494ec32000 CR3: 0000000071fc1000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 add_credits fs/smb/client/cifsglob.h:857 [inline]
 compound_send_recv+0x1254/0x3040 fs/smb/client/transport.c:1193
 cifs_send_recv+0x40/0x50 fs/smb/client/transport.c:1317
 SMB2_negotiate+0x16b5/0x4270 fs/smb/client/smb2pdu.c:1144
 cifs_negotiate_protocol+0x445/0x670 fs/smb/client/connect.c:4008
 cifs_get_smb_ses+0x8d6/0x1b00 fs/smb/client/connect.c:2434
 cifs_mount_get_session+0xef/0x440 fs/smb/client/connect.c:3472
 get_session fs/smb/client/dfs.c:62 [inline]
 dfs_mount_share+0x1e9/0x7b0 fs/smb/client/dfs.c:285
 cifs_mount+0xbc/0x650 fs/smb/client/connect.c:3720
 cifs_smb3_do_mount+0x2e5/0x710 fs/smb/client/cifsfs.c:950
 smb3_get_tree_common fs/smb/client/fs_context.c:785 [inline]
 smb3_get_tree+0x5a5/0xa90 fs/smb/client/fs_context.c:805
 vfs_get_tree+0x8c/0x280 fs/super.c:1772
 do_new_mount+0x24a/0xa40 fs/namespace.c:3386
 do_mount fs/namespace.c:3726 [inline]
 __do_sys_mount fs/namespace.c:3935 [inline]
 __se_sys_mount+0x2e7/0x3d0 fs/namespace.c:3912
 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: 0033:0x7f085779e159
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:00007f08586ae028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f0857a25fa0 RCX: 00007f085779e159
RDX: 0000200000000200 RSI: 0000200000000100 RDI: 0000200000000500
RBP: 00007f085783506b R08: 0000200000000300 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0857a26038 R14: 00007f0857a25fa0 R15: 00007fffde679eb8
 </TASK>

Crashes (30):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/19 16:33 linux-6.6.y 79643295eba1 853b104b .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/09/12 20:56 linux-6.6.y 8b73de7da85f 70a60e12 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/09/06 15:49 linux-6.6.y 8b73de7da85f 4f7b22a0 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/09/06 00:51 linux-6.6.y 8b73de7da85f 4f7b22a0 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/09/04 22:07 linux-6.6.y 8b73de7da85f f65209a4 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/08/22 06:55 linux-6.6.y c610b395b0a5 1e72964b .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/08/09 09:27 linux-6.6.y 6436c12a2ced 5d63f80b .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/08/01 14:50 linux-6.6.y a1153c0deb44 e611ffe1 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/09/19 13:44 linux-6.6.y 79643295eba1 853b104b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/09/19 13:41 linux-6.6.y 79643295eba1 853b104b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/09/16 15:25 linux-6.6.y 79643295eba1 12a0a44a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/09/14 21:27 linux-6.6.y 79643295eba1 81a27d1a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/09/11 20:38 linux-6.6.y 8b73de7da85f b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/09/11 20:37 linux-6.6.y 8b73de7da85f b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/09/10 01:56 linux-6.6.y 8b73de7da85f 4e8b1cc6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/09/10 01:39 linux-6.6.y 8b73de7da85f 4e8b1cc6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/09/06 13:38 linux-6.6.y 8b73de7da85f 4f7b22a0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/09/05 23:41 linux-6.6.y 8b73de7da85f 4f7b22a0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/09/05 23:40 linux-6.6.y 8b73de7da85f 4f7b22a0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/09/04 20:29 linux-6.6.y 8b73de7da85f f65209a4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/09/04 02:23 linux-6.6.y 8b73de7da85f 801f0966 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/09/03 13:41 linux-6.6.y 8b73de7da85f 6a988719 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/09/03 07:21 linux-6.6.y 8b73de7da85f 6a988719 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/08/22 05:19 linux-6.6.y c610b395b0a5 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/08/22 03:31 linux-6.6.y c610b395b0a5 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/08/20 13:07 linux-6.6.y c610b395b0a5 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/08/09 05:29 linux-6.6.y 6436c12a2ced 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/08/03 08:53 linux-6.6.y a1153c0deb44 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/08/01 06:07 linux-6.6.y a1153c0deb44 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
2026/07/28 12:45 linux-6.6.y c5596480c50e 45ae1df4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan WARNING in smb2_add_credits
* Struck through repros no longer work on HEAD.