KASAN: vmalloc-out-of-bounds Read in rpc_queue_upcall

Status: upstream: reported C repro on 2026/09/07 17:44
Subsystems: nfs net
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+d5c77cabf7a3492aa650@syzkaller.appspotmail.com
First crash: 4d06h, last: 4h18m
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
047ea71c repro-c Reproduced: ✅ ❓ KASAN: vmalloc-out-of-bounds Read in rpc_queue_upcall 2026/09/07 16:05 2026/09/07 16:05 2026/09/07 17:20 680aa3e1
0deded5f assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ✅ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ KASAN: vmalloc-out-of-bounds Read in rpc_queue_upcall 2026/09/05 00:00 2026/09/05 00:00 2026/09/05 00:09 7ce8fcf4
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [nfs?] [net?] KASAN: vmalloc-out-of-bounds Read in rpc_queue_upcall 1 (3) 2026/09/07 19:31
▶ ▼ Last patch testing requests (2)
Created Duration User Patch Repo Result
2026/09/07 19:15 14m cel@kernel.org git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux.git nfsd-testing no crash job log log
2026/09/07 17:31 12m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git df2908090cda368b01ff43709f51890076c56157 report job log log

Sample crash report:
 vmalloc memory
list_add corruption. prev->next should be next (ffff8880358a6c00), but was 0000000000000000. (prev=ffffc90003cbfa10).
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:32!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 2 UID: 0 PID: 5997 Comm: syz-executor965 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:__list_add_valid_or_report+0xfb/0x130 lib/list_debug.c:32
Code: b8 00 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 75 3d 49 8b 55 00 4c 89 e9 48 89 de 48 c7 c7 c0 12 62 8c e8 d6 35 ee fb 90 <0f> 0b 4c 89 e7 e8 bb 38 4b fd e9 3a ff ff ff 4c 89 ef e8 ae 38 4b
RSP: 0018:ffffc90003cbf938 EFLAGS: 00010282
RAX: 0000000000000075 RBX: ffff8880358a6c00 RCX: 0000000000000000
RDX: 0000000000000075 RSI: ffffffff81ea06f9 RDI: fffff52000797f18
RBP: ffffc90003cbfa10 R08: 0000000000000007 R09: 0000000000000000
R10: 8000000000000001 R11: 0000000000000001 R12: ffff8880358a6c08
R13: ffffc90003cbfa10 R14: ffff8880358a6c08 R15: ffffc90003cbfa10
FS:  00007f6eeac506c0(0000) GS:ffff8880d5d5d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbbfc3d4000 CR3: 0000000026a53000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 __list_add_valid include/linux/list.h:104 [inline]
 __list_add include/linux/list.h:169 [inline]
 list_add_tail include/linux/list.h:206 [inline]
 rpc_queue_upcall+0x2ff/0x530 net/sunrpc/rpc_pipe.c:142
 __cld_pipe_upcall fs/nfsd/nfs4recover.c:668 [inline]
 cld_pipe_upcall fs/nfsd/nfs4recover.c:691 [inline]
 nfsd4_cld_grace_start fs/nfsd/nfs4recover.c:1305 [inline]
 nfsd4_cld_tracking_init+0x85a/0x10f0 fs/nfsd/nfs4recover.c:1494
 nfsd4_client_tracking_init+0xe5/0x1c0 fs/nfsd/nfs4recover.c:1941
 nfs4_state_start_net.cold+0xb7/0x480 fs/nfsd/nfs4state.c:9838
 nfsd_startup_net fs/nfsd/nfssvc.c:391 [inline]
 nfsd_svc+0x54a/0x7d0 fs/nfsd/nfssvc.c:775
 write_threads+0x316/0x600 fs/nfsd/nfsctl.c:438
 nfsctl_transaction_write+0x106/0x1a0 fs/nfsd/nfsctl.c:114
 vfs_write+0x2aa/0x1050 fs/read_write.c:685
 ksys_write+0x12a/0x250 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6eeaca601e
Code: 08 0f 85 f5 e2 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 90 41 57 41 56 4d 89 c6 41 55 4d 89 cd 41 54 55 53 48 83 ec 08
RSP: 002b:00007f6eeac501a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f6eeac506c0 RCX: 00007f6eeaca601e
RDX: 0000000000000002 RSI: 00007f6eeacf10e4 RDI: 0000000000000003
RBP: 0000000000000021 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffd0
R13: 0000000000000000 R14: 00007ffe260d9b80 R15: 00007ffe260d9c68
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__list_add_valid_or_report+0xfb/0x130 lib/list_debug.c:32
Code: b8 00 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 75 3d 49 8b 55 00 4c 89 e9 48 89 de 48 c7 c7 c0 12 62 8c e8 d6 35 ee fb 90 <0f> 0b 4c 89 e7 e8 bb 38 4b fd e9 3a ff ff ff 4c 89 ef e8 ae 38 4b
RSP: 0018:ffffc90003cbf938 EFLAGS: 00010282
RAX: 0000000000000075 RBX: ffff8880358a6c00 RCX: 0000000000000000
RDX: 0000000000000075 RSI: ffffffff81ea06f9 RDI: fffff52000797f18
RBP: ffffc90003cbfa10 R08: 0000000000000007 R09: 0000000000000000
R10: 8000000000000001 R11: 0000000000000001 R12: ffff8880358a6c08
R13: ffffc90003cbfa10 R14: ffff8880358a6c08 R15: ffffc90003cbfa10
FS:  00007f6eeac506c0(0000) GS:ffff8880d5d5d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbbfc3d4000 CR3: 0000000026a53000 CR4: 0000000000352ef0

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/07 17:43 git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git df2908090cda 6a988719 .config console log report C ci-qemu-upstream BUG: corrupted list in rpc_queue_upcall
2026/09/03 17:51 upstream 940de590b839 6a988719 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: vmalloc-out-of-bounds Read in rpc_queue_upcall
2026/09/03 15:59 upstream 940de590b839 6a988719 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root KASAN: vmalloc-out-of-bounds Read in rpc_queue_upcall
2026/09/03 15:48 upstream 940de590b839 6a988719 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: vmalloc-out-of-bounds Read in rpc_queue_upcall
2026/09/03 15:46 upstream 940de590b839 6a988719 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root KASAN: vmalloc-out-of-bounds Read in rpc_queue_upcall
* Struck through repros no longer work on HEAD.