[v5.15] Internal error in futex_wait_setup

[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=12751434580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9e47345638b85bd0
dashboard link: https://syzkaller.appspot.com/bug?extid=7559a3a9d6c1a032519e
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+7559a3...@syzkaller.appspotmail.com

Internal error: Oops - BTI: 0000000036000001 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 4339 Comm: syz.3.78 Not tainted 5.15.189-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025
pstate: 42400405 (nZcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=jc)
pc : get_futex_value_locked kernel/futex/core.c:793 [inline]
pc : futex_wait_setup+0x1c4/0x4d4 kernel/futex/core.c:2916
lr : __uaccess_mask_ptr arch/arm64/include/asm/uaccess.h:239 [inline]
lr : get_futex_value_locked kernel/futex/core.c:790 [inline]
lr : futex_wait_setup+0x1a4/0x4d4 kernel/futex/core.c:2916
sp : ffff80001f637810
x29: ffff80001f637840 x28: ffff0000d2149b64 x27: 0000000000000000
x26: 1fffe0001a42936c x25: ffff0000d2149b40 x24: 00000000fffffff2
x23: 0000000000000000 x22: 1ffff00003ec6f2d x21: dfff800000000000
x20: 0000000000000000 x19: ffff80001f637968 x18: 0000000000000000
x17: 0000000000000002 x16: ffff8000083c6ed8 x15: 000000000000000d
x14: 0000000000ff0100 x13: 1ffff0000282e06b x12: 0000000000080000
x11: 000000000000013b x10: 0000ffffffffffff x9 : 0000000000000000
x8 : 0000000000000000 x7 : ffff8000083c8524 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000001 x3 : ffff8000082d608c
x2 : 0000000000000001 x1 : 0000000000000001 x0 : 0000000000000000
Call trace:
get_futex_value_locked kernel/futex/core.c:790 [inline]
futex_wait_setup+0x1c4/0x4d4 kernel/futex/core.c:2916
futex_wait_requeue_pi kernel/futex/core.c:3458 [inline]
do_futex+0x1bc8/0x257c kernel/futex/core.c:4005
__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: d503229f 2a1b03f8 2a1b03e0 b8400914 (2a1803e1)
---[ end trace 98822e0dd93ed1b0 ]---
----------------
Code disassembly (best guess):
0: d503229f csdb
4: 2a1b03f8 mov w24, w27
8: 2a1b03e0 mov w0, w27
c: b8400914 ldtr w20, [x8]
* 10: 2a1803e1 mov w1, w24 <-- 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=13a249a2580000

kernel config: https://syzkaller.appspot.com/x/.config?x=9e47345638b85bd0
dashboard link: https://syzkaller.appspot.com/bug?extid=7559a3a9d6c1a032519e
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=106401a2580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17a249a2580000

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+7559a3...@syzkaller.appspotmail.com

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

CPU: 1 PID: 4218 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: 42400405 (nZcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=jc)
pc : get_futex_value_locked kernel/futex/core.c:793 [inline]
pc : futex_wait_setup+0x1c4/0x4d4 kernel/futex/core.c:2916
lr : __uaccess_mask_ptr arch/arm64/include/asm/uaccess.h:239 [inline]
lr : get_futex_value_locked kernel/futex/core.c:790 [inline]
lr : futex_wait_setup+0x1a4/0x4d4 kernel/futex/core.c:2916

sp : ffff80001fcb7810
x29: ffff80001fcb7840 x28: ffff0000da321b64 x27: 0000000000000000
x26: 1fffe0001b46436c x25: ffff0000da321b40 x24: 00000000fffffff2
x23: 0000000000000000 x22: 1ffff00003f96f2d x21: dfff800000000000
x20: 0000000000000000 x19: ffff80001fcb7968 x18: 0000000000000000
x17: 0000000000000000 x16: ffff8000083c6ed8 x15: 000000000000000d
x14: 0000000000ff0100 x13: 1ffff0000282e06b x12: 0000000000ff0100
x11: 0000000000000001 x10: 0000ffffffffffff x9 : 0000000000000000

x8 : 0000000000000000 x7 : ffff8000083c8524 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000001 x3 : ffff8000082d608c
x2 : 0000000000000001 x1 : 0000000000000001 x0 : 0000000000000000
Call trace:
get_futex_value_locked kernel/futex/core.c:790 [inline]
futex_wait_setup+0x1c4/0x4d4 kernel/futex/core.c:2916
futex_wait_requeue_pi kernel/futex/core.c:3458 [inline]
do_futex+0x1bc8/0x257c kernel/futex/core.c:4005
__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: d503229f 2a1b03f8 2a1b03e0 b8400914 (2a1803e1)

---[ end trace e42cd3bf22213361 ]---

----------------
Code disassembly (best guess):
0: d503229f csdb
4: 2a1b03f8 mov w24, w27
8: 2a1b03e0 mov w0, w27
c: b8400914 ldtr w20, [x8]
* 10: 2a1803e1 mov w1, w24 <-- trapping instruction


---

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