[v5.15] Internal error in ep_poll

[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=1324b2f0580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9e47345638b85bd0
dashboard link: https://syzkaller.appspot.com/bug?extid=948c31b6f3713bfbfeb4
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+948c31...@syzkaller.appspotmail.com

Internal error: Oops - BTI: 0000000036000001 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 4314 Comm: syz.3.55 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 : epoll_put_uevent include/linux/eventpoll.h:81 [inline]
pc : ep_send_events fs/eventpoll.c:1732 [inline]
pc : ep_poll+0x854/0x1598 fs/eventpoll.c:1861
lr : epoll_put_uevent include/linux/eventpoll.h:81 [inline]
lr : ep_send_events fs/eventpoll.c:1732 [inline]
lr : ep_poll+0x82c/0x1598 fs/eventpoll.c:1861
sp : ffff80001b8f79a0
x29: ffff80001b8f7ba0 x28: 1fffe0001916ff0b x27: dfff800000000000
x26: 1fffe00019d55004 x25: ffff0000c8b7f858 x24: 0000000000000000
x23: 0000000020000480 x22: 0000000000000008 x21: ffff0000c8b7f860
x20: ffff0000c8b7f8a0 x19: 00000000fffffff2 x18: 0000000000000000
x17: 0000000000000000 x16: ffff800008a01258 x15: 0000000000000000
x14: 0000000000000000 x13: 1ffff0000282e06b x12: 0000000000ff0100
x11: 0000000000000000 x10: 0000ffffffffffff x9 : 0000000020000480
x8 : 0000000020000480 x7 : ffff800008750ed4 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000001
x2 : 0000000000000008 x1 : 0000000000000001 x0 : 0000000000000000
Call trace:
epoll_put_uevent include/linux/eventpoll.h:81 [inline]
ep_send_events fs/eventpoll.c:1732 [inline]
ep_poll+0x854/0x1598 fs/eventpoll.c:1861
do_epoll_wait+0x1a0/0x218 fs/eventpoll.c:2296
do_epoll_pwait+0x70/0x19c fs/eventpoll.c:2330
__do_sys_epoll_pwait fs/eventpoll.c:2343 [inline]
__se_sys_epoll_pwait fs/eventpoll.c:2337 [inline]
__arm64_sys_epoll_pwait+0x1e0/0x234 fs/eventpoll.c:2337
__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: b940dff8 2a1803f3 2a1803e0 b8000936 (2a1303e1)
---[ end trace e98b9da92465cc72 ]---
----------------
Code disassembly (best guess):
0: b940dff8 ldr w24, [sp, #220]
4: 2a1803f3 mov w19, w24
8: 2a1803e0 mov w0, w24
c: b8000936 sttr w22, [x9]
* 10: 2a1303e1 mov w1, w19 <-- 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=1307a5a2580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9e47345638b85bd0
dashboard link: https://syzkaller.appspot.com/bug?extid=948c31b6f3713bfbfeb4
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=15b7cda2580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1653f5a2580000

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+948c31...@syzkaller.appspotmail.com

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

CPU: 1 PID: 4182 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 : epoll_put_uevent include/linux/eventpoll.h:81 [inline]
pc : ep_send_events fs/eventpoll.c:1732 [inline]
pc : ep_poll+0x854/0x1598 fs/eventpoll.c:1861
lr : epoll_put_uevent include/linux/eventpoll.h:81 [inline]
lr : ep_send_events fs/eventpoll.c:1732 [inline]
lr : ep_poll+0x82c/0x1598 fs/eventpoll.c:1861

sp : ffff80001f6079c0
x29: ffff80001f607bc0 x28: 1fffe0001904b39b x27: dfff800000000000
x26: 1fffe000190f4a3c x25: ffff0000c8259cd8 x24: 0000000000000000
x23: 0000000020000280 x22: 0000000000000008 x21: ffff0000c8259ce0
x20: ffff0000c8259d20 x19: 00000000fffffff2 x18: 0000000000000000

x17: 0000000000000000 x16: ffff800008a01258 x15: 0000000000000000
x14: 0000000000000000 x13: 1ffff0000282e06b x12: 0000000000ff0100

x11: 0000000000000000 x10: 0000ffffffffffff x9 : 0000000020000280
x8 : 0000000020000280 x7 : ffff800008750ed4 x6 : 0000000000000000

x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000001
x2 : 0000000000000008 x1 : 0000000000000001 x0 : 0000000000000000
Call trace:
epoll_put_uevent include/linux/eventpoll.h:81 [inline]
ep_send_events fs/eventpoll.c:1732 [inline]
ep_poll+0x854/0x1598 fs/eventpoll.c:1861
do_epoll_wait+0x1a0/0x218 fs/eventpoll.c:2296
do_epoll_pwait+0x70/0x19c fs/eventpoll.c:2330

__do_sys_epoll_pwait2 fs/eventpoll.c:2362 [inline]
__se_sys_epoll_pwait2 fs/eventpoll.c:2348 [inline]
__arm64_sys_epoll_pwait2+0x184/0x208 fs/eventpoll.c:2348

__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: b940dff8 2a1803f3 2a1803e0 b8000936 (2a1303e1)

---[ end trace 71653509234f3c8c ]---

----------------
Code disassembly (best guess):
0: b940dff8 ldr w24, [sp, #220]
4: 2a1803f3 mov w19, w24
8: 2a1803e0 mov w0, w24
c: b8000936 sttr w22, [x9]
* 10: 2a1303e1 mov w1, w19 <-- trapping instruction


---

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