[v5.15] Internal error in exit_robust_list

[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=108d3ea2580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9e47345638b85bd0
dashboard link: https://syzkaller.appspot.com/bug?extid=4f684914f0d7d3c106a8
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+4f6849...@syzkaller.appspotmail.com

Internal error: Oops - BTI: 0000000036000001 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 4732 Comm: syz.3.270 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 : fetch_robust_entry kernel/futex/core.c:3762 [inline]
pc : exit_robust_list+0x414/0x5f0 kernel/futex/core.c:3813
lr : fetch_robust_entry kernel/futex/core.c:3762 [inline]
lr : exit_robust_list+0x3f0/0x5f0 kernel/futex/core.c:3813
sp : ffff80001efe7750
x29: ffff80001efe7790 x28: dfff800000000000 x27: 00000000fffffff2
x26: 0000000000000000 x25: 1fffe0001a185a3c x24: 0000000020000500
x23: 0000000000000000 x22: 0000000000000000 x21: ffff0000d0c2d1e4
x20: ffff0000d0c2d1c0 x19: ffff0000d0c2d1c0 x18: 0000000000000000
x17: 0000000000000002 x16: ffff8000083c52c8 x15: 00000000fffffe00
x14: 0000000000ff0100 x13: 1ffff0000282e06b x12: 0000000000ff0100
x11: 0000000000000000 x10: 0000ffffffffffff x9 : 0000000000000000
x8 : 0000000000000000 x7 : ffff800008750ed4 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000001
x2 : 0000000000000008 x1 : 0000000000000001 x0 : 0000000000000000
Call trace:
fetch_robust_entry kernel/futex/core.c:3762 [inline]
exit_robust_list+0x414/0x5f0 kernel/futex/core.c:3813
futex_cleanup kernel/futex/core.c:3845 [inline]
futex_exit_release+0x124/0x1ac kernel/futex/core.c:3946
exit_mm_release+0x24/0x40 kernel/fork.c:1431
exit_mm+0xa4/0x684 kernel/exit.c:488
do_exit+0x4ec/0x1f58 kernel/exit.c:870
do_group_exit+0x100/0x268 kernel/exit.c:997
get_signal+0x73c/0x1340 kernel/signal.c:2900
do_signal arch/arm64/kernel/signal.c:893 [inline]
do_notify_resume+0x35c/0x3128 arch/arm64/kernel/signal.c:946
prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline]
exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline]
el0_svc+0xf0/0x1e0 arch/arm64/kernel/entry-common.c:609
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 2a1703fb 2a1703e0 f840093a (2a1b03e1)
---[ end trace e7d248f6035d58bf ]---
----------------
Code disassembly (best guess):
0: d503229f csdb
4: 2a1703fb mov w27, w23
8: 2a1703e0 mov w0, w23
c: f840093a ldtr x26, [x9]
* 10: 2a1b03e1 mov w1, w27 <-- 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=1591b1a2580000

kernel config: https://syzkaller.appspot.com/x/.config?x=9e47345638b85bd0
dashboard link: https://syzkaller.appspot.com/bug?extid=4f684914f0d7d3c106a8
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=11f33434580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15f33434580000

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+4f6849...@syzkaller.appspotmail.com

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

CPU: 0 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 : fetch_robust_entry kernel/futex/core.c:3762 [inline]
pc : exit_robust_list+0x414/0x5f0 kernel/futex/core.c:3813
lr : fetch_robust_entry kernel/futex/core.c:3762 [inline]
lr : exit_robust_list+0x3f0/0x5f0 kernel/futex/core.c:3813

sp : ffff80001fe979f0
x29: ffff80001fe97a30 x28: dfff800000000000 x27: 00000000fffffff2
x26: 0000000000000000 x25: 1fffe0001ad03004 x24: 0000000020000500
x23: 0000000000000000 x22: 0000000000000000 x21: ffff0000d6818024
x20: ffff0000d6818000 x19: ffff0000d6818000 x18: 0000000000000000
x17: 0000000000000000 x16: ffff8000083c52c8 x15: 0000000000000000
x14: 0000000000000000 x13: 1ffff0000282e06b x12: 0000000000ff0100

x11: 0000000000000000 x10: 0000ffffffffffff x9 : 0000000000000000
x8 : 0000000000000000 x7 : ffff800008750ed4 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000001
x2 : 0000000000000008 x1 : 0000000000000001 x0 : 0000000000000000
Call trace:
fetch_robust_entry kernel/futex/core.c:3762 [inline]
exit_robust_list+0x414/0x5f0 kernel/futex/core.c:3813
futex_cleanup kernel/futex/core.c:3845 [inline]
futex_exit_release+0x124/0x1ac kernel/futex/core.c:3946
exit_mm_release+0x24/0x40 kernel/fork.c:1431
exit_mm+0xa4/0x684 kernel/exit.c:488
do_exit+0x4ec/0x1f58 kernel/exit.c:870
do_group_exit+0x100/0x268 kernel/exit.c:997

__do_sys_exit_group kernel/exit.c:1008 [inline]
__se_sys_exit_group kernel/exit.c:1006 [inline]
__wake_up_parent+0x0/0x60 kernel/exit.c:1006
__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 2a1703fb 2a1703e0 f840093a (2a1b03e1)

---[ end trace 06d582ef56963f84 ]---

----------------
Code disassembly (best guess):
0: d503229f csdb
4: 2a1703fb mov w27, w23
8: 2a1703e0 mov w0, w23
c: f840093a ldtr x26, [x9]
* 10: 2a1b03e1 mov w1, w27 <-- trapping instruction


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