Internal error in futex_wake_op

Status: upstream: reported C repro on 2026/08/27 18:52
Subsystems: kernel
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+417a6b7c02d5d03f9aa6@syzkaller.appspotmail.com
First crash: 1d08h, last: 1d08h
▶ ▼ ✨ AI Patch Versions (1)
Version Stage Reported Report Link Job
1 moderation 2026/08/27 23:04 Discussion e80ac460-6a7b-4d71-8092-1edf4242c342
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
e80ac460 patching ❓ Internal error in futex_wake_op 2026/08/27 19:17 2026/08/27 19:17 2026/08/27 23:03 bd6de8ec
74349278 assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ Internal error in futex_wake_op 2026/08/27 14:18 2026/08/27 14:18 2026/08/27 14:25 bd6de8ec
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Title Replies (including bot) Last reply
[syzbot] [kernel?] Internal error in futex_wake_op 0 (1) 2026/08/27 18:52

Sample crash report:
futex_wake_op: syz.0.17 tries to shift op by 144; fix this program
Internal error: synchronous external abort: 0000000096000010 [#1]  SMP
Modules linked in:
CPU: 0 UID: 0 PID: 4917 Comm: syz.0.17 Tainted: G   M                syzkaller #0 PREEMPT 
Tainted: [M]=MACHINE_CHECK
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/07/2026
pstate: 83000005 (Nzcv daif -PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : __llsc_futex_atomic_or arch/arm64/include/asm/futex.h:51 [inline]
pc : __futex_atomic_or arch/arm64/include/asm/futex.h:239 [inline]
pc : arch_futex_atomic_op_inuser arch/arm64/include/asm/futex.h:269 [inline]
pc : futex_atomic_op_inuser kernel/futex/waitwake.c:251 [inline]
pc : futex_wake_op+0x450/0xfe8 kernel/futex/waitwake.c:302
lr : mte_enable_tco arch/arm64/include/asm/mte-kasan.h:62 [inline]
lr : uaccess_enable_privileged arch/arm64/include/asm/uaccess.h:147 [inline]
lr : __llsc_futex_atomic_or arch/arm64/include/asm/futex.h:51 [inline]
lr : __futex_atomic_or arch/arm64/include/asm/futex.h:239 [inline]
lr : arch_futex_atomic_op_inuser arch/arm64/include/asm/futex.h:269 [inline]
lr : futex_atomic_op_inuser kernel/futex/waitwake.c:251 [inline]
lr : futex_wake_op+0x43c/0xfe8 kernel/futex/waitwake.c:302
sp : ffff800093197980
x29: ffff800093197b40 x28: 0000000000010000 x27: 0000000000000000
x26: 1fffe00018d2a3ad x25: dfff800000000000 x24: ffff0000c6951d40
x23: ffff0000c6951d6c x22: 0000000000000002 x21: 1fffe00018d2a685
x20: ffff0000c1df3780 x19: ffff0000c695342c x18: 0000000000000000
x17: 72676f7270207369 x16: 687420786966203b x15: 3434312079622070
x14: 6f20746669687320 x13: 0000000000000001 x12: 0000000000000000
x11: 0000000000000000 x10: 00000000fffffff5 x9 : 0000000000000000
x8 : 0000000000000080 x7 : ffff80008048c60c x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff8000805b0678
x2 : 0000000000000002 x1 : ffff0000c6951d40 x0 : 0000000000000000
Call trace:
 __llsc_futex_atomic_or arch/arm64/include/asm/futex.h:51 [inline] (P)
 __futex_atomic_or arch/arm64/include/asm/futex.h:239 [inline] (P)
 arch_futex_atomic_op_inuser arch/arm64/include/asm/futex.h:269 [inline] (P)
 futex_atomic_op_inuser kernel/futex/waitwake.c:251 [inline] (P)
 futex_wake_op+0x450/0xfe8 kernel/futex/waitwake.c:302 (P)
 do_futex+0x200/0x378 kernel/futex/syscalls.c:144
 __do_sys_futex kernel/futex/syscalls.c:210 [inline]
 __se_sys_futex kernel/futex/syscalls.c:191 [inline]
 __arm64_sys_futex+0x2e4/0x418 kernel/futex/syscalls.c:191
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:758
 el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:777
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:590
Code: d500409f 1280014a f94057eb f9800171 (885f7d76) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	d500409f 	msr	pan, #0x0
   4:	1280014a 	mov	w10, #0xfffffff5            	// #-11
   8:	f94057eb 	ldr	x11, [sp, #168]
   c:	f9800171 	prfm	pstl1strm, [x11]
* 10:	885f7d76 	ldxr	w22, [x11] <-- trapping instruction

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/27 14:02 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 68f892e99df9 a2b77b9e .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 Internal error in futex_wake_op
* Struck through repros no longer work on HEAD.