[v5.15] Internal error in do_futex

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c79648372d02 Linux 5.15.189
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17ed55bc580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9e47345638b85bd0
dashboard link: https://syzkaller.appspot.com/bug?extid=ffd41ddff802e9784046
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
userspace arch: arm64

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7ab49562317a/disk-c7964837.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e847ec1e38d3/vmlinux-c7964837.xz
kernel image: https://storage.googleapis.com/syzbot-assets/263158c6371c/Image-c7964837.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ffd41d...@syzkaller.appspotmail.com

Internal error: Oops - BTI: 0000000036000001 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 4876 Comm: syz.4.315 Not tainted 5.15.189-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025
pstate: 82000405 (Nzcv daif -PAN -UAO +TCO -DIT -SSBS BTYPE=jc)
pc : arch_futex_atomic_op_inuser arch/arm64/include/asm/futex.h:60 [inline]
pc : futex_atomic_op_inuser kernel/futex/core.c:1729 [inline]
pc : futex_wake_op kernel/futex/core.c:1779 [inline]
pc : do_futex+0x804/0x257c kernel/futex/core.c:3993
lr : __uaccess_enable_tco arch/arm64/include/asm/uaccess.h:188 [inline]
lr : uaccess_enable_privileged arch/arm64/include/asm/uaccess.h:221 [inline]
lr : arch_futex_atomic_op_inuser arch/arm64/include/asm/futex.h:60 [inline]
lr : futex_atomic_op_inuser kernel/futex/core.c:1729 [inline]
lr : futex_wake_op kernel/futex/core.c:1779 [inline]
lr : do_futex+0x7d0/0x257c kernel/futex/core.c:3993
sp : ffff8000201078a0
x29: ffff800020107c20 x28: 00000000fffffff2 x27: 0000000011000000
x26: ffff0000c2343680 x25: 0000000000000001 x24: 0000000000000001
x23: 0000000000000000 x22: 0000000000000000 x21: 0000000000000000
x20: 0000000000000000 x19: 1fffe00018468979 x18: 0000000000000001
x17: 0000000000000002 x16: ffff8000083bf97c x15: 0000000000000004
x14: 0000000000ff0100 x13: ffffffffffffffff x12: 0000000000000000
x11: 00000000fffffff5 x10: 00000000fffffff2 x9 : ffff8000083bf948
x8 : 0000000000000080 x7 : ffff8000083bf6f4 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000001 x3 : ffff8000082d608c
x2 : 0000000000000001 x1 : ffff80001435cb90 x0 : 0000000000000001
Call trace:
arch_futex_atomic_op_inuser arch/arm64/include/asm/futex.h:60 [inline]
futex_atomic_op_inuser kernel/futex/core.c:1729 [inline]
futex_wake_op kernel/futex/core.c:1779 [inline]
do_futex+0x804/0x257c kernel/futex/core.c:3993
__do_sys_futex kernel/futex/core.c:4059 [inline]
__se_sys_futex kernel/futex/core.c:4040 [inline]
__arm64_sys_futex+0x388/0x400 kernel/futex/core.c:4040
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
Code: 3400009c 4b1c0108 35ffff68 2a0b03fc (d5033bbf)
---[ end trace 3c77146df4f451cc ]---
----------------
Code disassembly (best guess):
0: 3400009c cbz w28, 0x10
4: 4b1c0108 sub w8, w8, w28
8: 35ffff68 cbnz w8, 0xfffffffffffffff4
c: 2a0b03fc mov w28, w11
* 10: d5033bbf dmb ish <-- trapping instruction


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: c79648372d02 Linux 5.15.189
git tree: linux-5.15.y

console output: https://syzkaller.appspot.com/x/log.txt?x=174b3434580000

kernel config: https://syzkaller.appspot.com/x/.config?x=9e47345638b85bd0
dashboard link: https://syzkaller.appspot.com/bug?extid=ffd41ddff802e9784046
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
userspace arch: arm64

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1652f2f0580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=102249a2580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7ab49562317a/disk-c7964837.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e847ec1e38d3/vmlinux-c7964837.xz
kernel image: https://storage.googleapis.com/syzbot-assets/263158c6371c/Image-c7964837.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ffd41d...@syzkaller.appspotmail.com

Internal error: Oops - BTI: 0000000036000001 [#1] PREEMPT SMP
Modules linked in:

CPU: 0 PID: 4186 Comm: syz.0.17 Not tainted 5.15.189-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025
pstate: 82000405 (Nzcv daif -PAN -UAO +TCO -DIT -SSBS BTYPE=jc)
pc : arch_futex_atomic_op_inuser arch/arm64/include/asm/futex.h:60 [inline]
pc : futex_atomic_op_inuser kernel/futex/core.c:1729 [inline]
pc : futex_wake_op kernel/futex/core.c:1779 [inline]
pc : do_futex+0x804/0x257c kernel/futex/core.c:3993
lr : __uaccess_enable_tco arch/arm64/include/asm/uaccess.h:188 [inline]
lr : uaccess_enable_privileged arch/arm64/include/asm/uaccess.h:221 [inline]
lr : arch_futex_atomic_op_inuser arch/arm64/include/asm/futex.h:60 [inline]
lr : futex_atomic_op_inuser kernel/futex/core.c:1729 [inline]
lr : futex_wake_op kernel/futex/core.c:1779 [inline]
lr : do_futex+0x7d0/0x257c kernel/futex/core.c:3993

sp : ffff80001fce78a0
x29: ffff80001fce7c20 x28: 00000000fffffff2 x27: 0000000011000000
x26: ffff0000cd5e51c0 x25: 0000000000000001 x24: 0000000000000001

x23: 0000000000000000 x22: 0000000000000000 x21: 0000000000000000

x20: 0000000000000000 x19: 1fffe00019abcce1 x18: 0000000000000001
x17: 0000000000000000 x16: ffff8000083bf97c x15: 0000000000000004

x14: 0000000000ff0100 x13: ffffffffffffffff x12: 0000000000000000
x11: 00000000fffffff5 x10: 00000000fffffff2 x9 : ffff8000083bf948
x8 : 0000000000000080 x7 : ffff8000083bf6f4 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000001 x3 : ffff8000082d608c
x2 : 0000000000000001 x1 : ffff80001435cb90 x0 : 0000000000000001
Call trace:
arch_futex_atomic_op_inuser arch/arm64/include/asm/futex.h:60 [inline]
futex_atomic_op_inuser kernel/futex/core.c:1729 [inline]
futex_wake_op kernel/futex/core.c:1779 [inline]
do_futex+0x804/0x257c kernel/futex/core.c:3993
__do_sys_futex kernel/futex/core.c:4059 [inline]
__se_sys_futex kernel/futex/core.c:4040 [inline]
__arm64_sys_futex+0x388/0x400 kernel/futex/core.c:4040
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
Code: 3400009c 4b1c0108 35ffff68 2a0b03fc (d5033bbf)

---[ end trace 0af46781fdb8c899 ]---

----------------
Code disassembly (best guess):
0: 3400009c cbz w28, 0x10
4: 4b1c0108 sub w8, w8, w28
8: 35ffff68 cbnz w8, 0xfffffffffffffff4
c: 2a0b03fc mov w28, w11
* 10: d5033bbf dmb ish <-- trapping instruction


---

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