WARNING in smb2_add_credits

Status: upstream: reported syz repro on 2026/08/01 00:35
Subsystems: cifs
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+eeb58d2197d88720a228@syzkaller.appspotmail.com
First crash: 6d12h, last: 1h49m
✨ AI Patch Versions (1)
Version Stage Reported Report Link Job
1 moderation 2026/08/03 09:32 Discussion 53130d26-0860-4523-bf44-fbc757857958
✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision Error
53130d26 patching WARNING in smb2_add_credits 2026/08/03 07:44 2026/08/03 07:44 2026/08/03 09:32 e611ffe1

			
		
9fa9fafc assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ✅ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ WARNING in smb2_add_credits 2026/07/29 01:42 2026/07/29 01:42 2026/07/29 02:25 7be3c40b

			
		
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [cifs?] WARNING in smb2_add_credits 0 (1) 2026/08/01 00:35
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 WARNING in smb2_add_credits -1 syz 4 4h06m 6d00h 0/2 upstream: reported syz repro on 2026/07/28 12:45

Sample crash report:
cifs_smb3_do_mount: 16 callbacks suppressed
CIFS: Attempting to mount //127.0.0.1/share
CIFS: VFS: \\127.0.0.1 Error -104 sending data on socket to server
------------[ cut here ]------------
server->in_flight == 0
WARNING: fs/smb/client/smb2ops.c:104 at smb2_add_credits+0x1249/0x2b70 fs/smb/client/smb2ops.c:104, CPU#1: syz.2.396/7613
Modules linked in:
CPU: 1 UID: 0 PID: 7613 Comm: syz.2.396 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:smb2_add_credits+0x1249/0x2b70 fs/smb/client/smb2ops.c:104
Code: de 83 e6 01 31 ff e8 d6 23 be fe f6 c3 01 75 0a e8 8c 1f be fe e9 22 13 00 00 0f 1f 44 00 00 e8 7d 1f be fe e9 13 13 00 00 90 <0f> 0b 90 80 3d 4e 2a 38 0d 01 0f 85 9e 03 00 00 e8 62 1f be fe 49
RSP: 0018:ffffc90005e7f238 EFLAGS: 00010246
RAX: ffffffff8308e708 RBX: 1ffff1100f7f4c61 RCX: 0000000000000000
RDX: ffff888031015d00 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000200 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff83091460 R12: ffff88807bfa6308
R13: ffffc90005e7f450 R14: ffff88807bfa6000 R15: 0000000000000000
FS:  00007f48948f26c0(0000) GS:ffff88812504c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2822333d58 CR3: 000000003498a000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 add_credits fs/smb/client/cifsglob.h:894 [inline]
 compound_send_recv+0x13b4/0x2b90 fs/smb/client/transport.c:979
 cifs_send_recv+0x42/0x60 fs/smb/client/transport.c:1106
 SMB2_negotiate+0x164d/0x4030 fs/smb/client/smb2pdu.c:1188
 cifs_negotiate_protocol+0x45d/0x680 fs/smb/client/connect.c:4043
 cifs_get_smb_ses+0x1104/0x1ff0 fs/smb/client/connect.c:2492
 cifs_mount_get_session+0xf1/0x450 fs/smb/client/connect.c:3578
 get_session fs/smb/client/dfs.c:65 [inline]
 dfs_mount_share+0x22e/0x990 fs/smb/client/dfs.c:275
 cifs_mount+0xcc/0xbf0 fs/smb/client/connect.c:3860
 cifs_smb3_do_mount+0x2d0/0x8a0 fs/smb/client/cifsfs.c:1024
 smb3_get_tree_common fs/smb/client/fs_context.c:897 [inline]
 smb3_get_tree+0x2dd/0x400 fs/smb/client/fs_context.c:917
 vfs_get_tree+0x92/0x2a0 fs/super.c:1700
 fc_mount fs/namespace.c:1198 [inline]
 do_new_mount_fc fs/namespace.c:3765 [inline]
 do_new_mount+0x319/0xdc0 fs/namespace.c:3841
 do_mount fs/namespace.c:4174 [inline]
 __do_sys_mount fs/namespace.c:4390 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4367
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f489399e019
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:00007f48948f2028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f4893c26090 RCX: 00007f489399e019
RDX: 0000200000000400 RSI: 0000200000000300 RDI: 0000200000000200
RBP: 00007f4893a3500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4893c26128 R14: 00007f4893c26090 R15: 00007ffc0d226d38
 </TASK>

Crashes (35):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/02 05:50 upstream 2d2338c93da7 e611ffe1 .config strace log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root WARNING in smb2_add_credits
2026/07/28 02:01 upstream f5098b6bae76 4cb2b096 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING in smb2_add_credits
2026/08/03 11:11 upstream 075b74841bd0 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING in smb2_add_credits
2026/08/03 10:02 upstream bd1dde877520 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in smb2_add_credits
2026/08/03 09:05 upstream bd1dde877520 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in smb2_add_credits
2026/08/03 02:43 upstream bd1dde877520 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in smb2_add_credits
2026/08/03 00:46 upstream bd1dde877520 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root WARNING in smb2_add_credits
2026/08/03 00:03 upstream bd1dde877520 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in smb2_add_credits
2026/08/02 23:31 upstream bd1dde877520 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root WARNING in smb2_add_credits
2026/08/02 22:49 upstream bd1dde877520 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root WARNING in smb2_add_credits
2026/08/02 22:20 upstream bd1dde877520 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in smb2_add_credits
2026/08/02 03:20 upstream 2d2338c93da7 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root WARNING in smb2_add_credits
2026/08/01 12:07 upstream 0131b508c0e2 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING in smb2_add_credits
2026/07/31 23:26 upstream 8ba098e6b6ff 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in smb2_add_credits
2026/07/31 10:43 upstream 3708dd948844 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root WARNING in smb2_add_credits
2026/07/31 10:43 upstream 3708dd948844 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root WARNING in smb2_add_credits
2026/07/31 10:42 upstream 3708dd948844 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root WARNING in smb2_add_credits
2026/07/31 10:42 upstream 3708dd948844 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root WARNING in smb2_add_credits
2026/07/30 18:38 upstream 11028ab62899 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING in smb2_add_credits
2026/07/30 12:55 upstream 11028ab62899 2377cd3d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root WARNING in smb2_add_credits
2026/07/28 00:32 upstream f5098b6bae76 4cb2b096 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root WARNING in smb2_add_credits
2026/07/31 20:22 upstream 8ba098e6b6ff 7664cf44 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in smb2_add_credits
2026/07/31 16:38 upstream 8ba098e6b6ff 7664cf44 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in smb2_add_credits
2026/07/30 22:03 upstream 11028ab62899 0a1bc234 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in smb2_add_credits
2026/07/30 20:26 upstream 11028ab62899 0a1bc234 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in smb2_add_credits
2026/07/30 16:56 upstream 11028ab62899 0a1bc234 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in smb2_add_credits
2026/07/30 05:49 upstream fc46aed51f62 2377cd3d .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in smb2_add_credits
2026/07/30 03:36 upstream fc46aed51f62 2377cd3d .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in smb2_add_credits
2026/07/29 13:06 upstream fc02acf6ac0c b63596d1 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in smb2_add_credits
2026/07/28 15:24 upstream 62cc90241548 5fe7c56f .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in smb2_add_credits
2026/08/02 11:20 upstream 2d2338c93da7 e611ffe1 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in smb2_add_credits
2026/08/02 06:52 upstream 2d2338c93da7 e611ffe1 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in smb2_add_credits
2026/07/29 06:20 upstream 3b5f4b83c4ab 4a865b71 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in smb2_add_credits
2026/07/29 23:54 linux-next cc2b5f627e8c cb1587ea .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING in smb2_add_credits
2026/07/28 18:26 linux-next cc2b5f627e8c 19622d9d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING in smb2_add_credits
* Struck through repros no longer work on HEAD.