[v6.1] BUG: unable to handle kernel paging request in set_link_state

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syzbot

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Jul 24, 2026, 6:28:29 PM (2 days ago) Jul 24
to syzkaller...@googlegroups.com
Hello,

syzbot found the following issue on:

HEAD commit: dc5c83b7f5f8 Linux 6.1.178
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1777588e580000
kernel config: https://syzkaller.appspot.com/x/.config?x=872c04466179833f
dashboard link: https://syzkaller.appspot.com/bug?extid=dd6dbf1b89f9af46cb13
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/96393e4697a3/disk-dc5c83b7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0d4afce44fab/vmlinux-dc5c83b7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4787e310d875/Image-dc5c83b7.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+dd6dbf...@syzkaller.appspotmail.com

Unable to handle kernel paging request at virtual address dfff800000000000
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
Mem abort info:
ESR = 0x0000000096000006
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x06: level 2 translation fault
Data abort info:
ISV = 0, ISS = 0x00000006
CM = 0, WnR = 0
[dfff800000000000] address between user and kernel address ranges
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 7152 Comm: syz.7.641 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026
pstate: 824000c5 (Nzcv daIF +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : set_link_state+0x38/0xf38 drivers/usb/gadget/udc/dummy_hcd.c:435
lr : set_link_state+0x34/0xf38 drivers/usb/gadget/udc/dummy_hcd.c:434
sp : ffff800021a974b0
x29: ffff800021a97500 x28: ffff0000d1b96010 x27: dfff800000000000
x26: 1fffe0001a496189 x25: ffff80000dceb9e4 x24: dfff800000000000
x23: 0000000000000000 x22: 0000000000000000 x21: ffff0000d24b124a
x20: 0000000000000000 x19: 0000000000000000 x18: 0000000000000000
x17: 00000000ffff0000 x16: ffff8000082f2840 x15: ffff8000184cd000
x14: ffff700004352e90 x13: 1ffff00004352e90 x12: 0000000000080000
x11: 000000000000c850 x10: ffff8000236ea000 x9 : ffff80000dcec254
x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000020 x4 : 0000000000000000 x3 : ffff8000082f2968
x2 : 0000000000000001 x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
set_link_state+0x38/0xf38 drivers/usb/gadget/udc/dummy_hcd.c:435
dummy_pullup+0xd8/0x12c drivers/usb/gadget/udc/dummy_hcd.c:914
usb_gadget_disconnect_locked+0xf8/0x54c drivers/usb/gadget/udc/core.c:782
gadget_unbind_driver+0xa0/0x35c drivers/usb/gadget/udc/core.c:1696
device_remove drivers/base/dd.c:547 [inline]
__device_release_driver drivers/base/dd.c:1279 [inline]
device_release_driver_internal+0x3d4/0x6e4 drivers/base/dd.c:1305
device_release_driver+0x28/0x38 drivers/base/dd.c:1328
bus_remove_device+0x294/0x384 drivers/base/bus.c:531
device_del+0x580/0x990 drivers/base/core.c:3900
usb_del_gadget+0x160/0x214 drivers/usb/gadget/udc/core.c:1580
usb_del_gadget_udc+0x20/0x38 drivers/usb/gadget/udc/core.c:1603
dummy_udc_remove+0x54/0x68 drivers/usb/gadget/udc/dummy_hcd.c:1123
platform_remove+0x98/0xf0 drivers/base/platform.c:1422
device_remove drivers/base/dd.c:547 [inline]
__device_release_driver drivers/base/dd.c:1279 [inline]
device_release_driver_internal+0x3d4/0x6e4 drivers/base/dd.c:1305
device_driver_detach+0x48/0x58 drivers/base/dd.c:1341
unbind_store+0x2a8/0x2b4 drivers/base/bus.c:193
drv_attr_store+0x80/0xa4 drivers/base/bus.c:77
sysfs_kf_write+0x1f8/0x274 fs/sysfs/file.c:140
kernfs_fop_write_iter+0x390/0x4b4 fs/kernfs/file.c:352
call_write_iter include/linux/fs.h:2265 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x3c8/0x7c8 fs/read_write.c:584
ksys_write+0x12c/0x228 fs/read_write.c:637
__do_sys_write fs/read_write.c:649 [inline]
__se_sys_write fs/read_write.c:646 [inline]
__arm64_sys_write+0x7c/0x90 fs/read_write.c:646
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
Code: aa0003f4 f2fbfffb 969f1b84 d343fe88 (387b6908)
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
0: aa0003f4 mov x20, x0
4: f2fbfffb movk x27, #0xdfff, lsl #48
8: 969f1b84 bl 0xfffffffffa7c6e18
c: d343fe88 lsr x8, x20, #3
* 10: 387b6908 ldrb w8, [x8, x27] <-- trapping instruction


---
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syzbot

unread,
Jul 25, 2026, 7:39:24 AM (18 hours ago) Jul 25
to syzkaller...@googlegroups.com
syzbot has found a reproducer for the following issue on:

HEAD commit: dc5c83b7f5f8 Linux 6.1.178
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17bce1b9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=872c04466179833f
dashboard link: https://syzkaller.appspot.com/bug?extid=dd6dbf1b89f9af46cb13
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: arm64
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10d6d88e580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17fdc7b1580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/96393e4697a3/disk-dc5c83b7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0d4afce44fab/vmlinux-dc5c83b7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4787e310d875/Image-dc5c83b7.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+dd6dbf...@syzkaller.appspotmail.com

Unable to handle kernel paging request at virtual address dfff800000000000
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
Mem abort info:
ESR = 0x0000000096000006
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x06: level 2 translation fault
Data abort info:
ISV = 0, ISS = 0x00000006
CM = 0, WnR = 0
[dfff800000000000] address between user and kernel address ranges
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 4510 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026
pstate: 824000c5 (Nzcv daIF +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : set_link_state+0x38/0xf38 drivers/usb/gadget/udc/dummy_hcd.c:435
lr : set_link_state+0x34/0xf38 drivers/usb/gadget/udc/dummy_hcd.c:434
sp : ffff800021987520
x29: ffff800021987570 x28: 1fffe0001b475234 x27: dfff800000000000
x26: 1fffe00019f2e989 x25: ffff80000dceb9e4 x24: dfff800000000000
x23: 0000000000000000 x22: 0000000000000000 x21: ffff0000cf97524a
x20: 0000000000000000 x19: 0000000000000000 x18: 1fffe00033e7697e
x17: ffff80001537d000 x16: ffff8000082f2840 x15: 000000000004ffff
x14: ffff700004330ea0 x13: 1ffff00004330ea0 x12: 0000000000000004
x11: ff0080000dcec254 x10: 0000000000000000 x9 : ffff80000dcec254
x8 : 0000000000000000 x7 : ffff80000dceba78 x6 : 0000000000000000
x5 : 0000000000000080 x4 : 0000000000000001 x3 : ffff8000082f2968
x2 : 0000000000000001 x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
set_link_state+0x38/0xf38 drivers/usb/gadget/udc/dummy_hcd.c:435
dummy_pullup+0xd8/0x12c drivers/usb/gadget/udc/dummy_hcd.c:914
usb_gadget_disconnect_locked+0xf8/0x54c drivers/usb/gadget/udc/core.c:782
gadget_unbind_driver+0xa0/0x35c drivers/usb/gadget/udc/core.c:1696
device_remove drivers/base/dd.c:547 [inline]
__device_release_driver drivers/base/dd.c:1279 [inline]
device_release_driver_internal+0x3d4/0x6e4 drivers/base/dd.c:1305
driver_detach+0x1e8/0x2ac drivers/base/dd.c:1368
bus_remove_driver+0x120/0x240 drivers/base/bus.c:679
driver_unregister+0x78/0xac drivers/base/driver.c:274
usb_gadget_unregister_driver+0x50/0x78 drivers/usb/gadget/udc/core.c:1762
raw_release+0xc4/0x294 drivers/usb/gadget/legacy/raw_gadget.c:416
__fput+0x1b4/0x7b0 fs/file_table.c:320
____fput+0x20/0x30 fs/file_table.c:348
task_work_run+0x1f4/0x280 kernel/task_work.c:203
exit_task_work include/linux/task_work.h:39 [inline]
do_exit+0x54c/0x19ac kernel/exit.c:881
do_group_exit+0x198/0x238 kernel/exit.c:1024
get_signal+0x11f4/0x133c kernel/signal.c:2872
do_signal arch/arm64/kernel/signal.c:1095 [inline]
do_notify_resume+0x364/0x2c84 arch/arm64/kernel/signal.c:1148
prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
el0_svc+0x98/0x128 arch/arm64/kernel/entry-common.c:638
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
Code: aa0003f4 f2fbfffb 969f1b84 d343fe88 (387b6908)
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
0: aa0003f4 mov x20, x0
4: f2fbfffb movk x27, #0xdfff, lsl #48
8: 969f1b84 bl 0xfffffffffa7c6e18
c: d343fe88 lsr x8, x20, #3
* 10: 387b6908 ldrb w8, [x8, x27] <-- trapping instruction


---
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