[syzbot] [usb?] general protection fault in bus_remove_device

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syzbot

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Aug 19, 2026, 1:18:49 PM (18 hours ago) Aug 19
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Hello,

syzbot found the following issue on:

HEAD commit: 15ef2f78c49d Merge tag 'input-for-v7.2-rc7' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11b16949580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1d67342c314f228d
dashboard link: https://syzkaller.appspot.com/bug?extid=87188222c77c0dbbdb4d
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1198b279580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1598b279580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-15ef2f78.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/dc9c417e94c9/vmlinux-15ef2f78.xz
kernel image: https://storage.googleapis.com/syzbot-assets/db592e5f65db/bzImage-15ef2f78.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+871882...@syzkaller.appspotmail.com

usb 5-1: selecting invalid altsetting 0
usb 5-1: USB disconnect, device number 2
Oops: general protection fault, probably for non-canonical address 0xdffffc000000000b: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000058-0x000000000000005f]
CPU: 1 UID: 0 PID: 29 Comm: kworker/1:0 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Workqueue: usb_hub_wq hub_event
RIP: 0010:klist_put+0x4d/0x1d0 lib/klist.c:212
Code: c1 ea 03 80 3c 02 00 0f 85 74 01 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b 23 49 83 e4 fe 49 8d 7c 24 58 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 43 01 00 00 4c 89 e7 4d 8b 74 24 58 e8 7c 10 0d
RSP: 0018:ffffc90000687620 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff888036142880 RCX: 0000000000000000
RDX: 000000000000000b RSI: ffffffff8bb263a5 RDI: 0000000000000058
RBP: 0000000000000001 R08: 0000000000000000 R09: fffffbfff2247f98
R10: ffffffff9123fcc3 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000001 R14: ffffffff9123fc80 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880d5cde000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff41160ff4 CR3: 0000000033bb7000 CR4: 0000000000352ef0
Call Trace:
<TASK>
klist_del lib/klist.c:230 [inline]
klist_remove+0x14c/0x2e0 lib/klist.c:249
__device_release_driver drivers/base/dd.c:1357 [inline]
device_release_driver_internal+0x4fb/0x620 drivers/base/dd.c:1372
bus_remove_device+0x2bc/0x560 drivers/base/bus.c:664
device_del+0x376/0x9b0 drivers/base/core.c:3961
usb_disable_device+0x367/0x810 drivers/usb/core/message.c:1478
usb_disconnect+0x2e2/0x9a0 drivers/usb/core/hub.c:2345
hub_port_connect drivers/usb/core/hub.c:5415 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5715 [inline]
port_event drivers/usb/core/hub.c:5879 [inline]
hub_event+0x1bb1/0x4420 drivers/usb/core/hub.c:5961
process_one_work+0xa23/0x1940 kernel/workqueue.c:3322
process_scheduled_works kernel/workqueue.c:3405 [inline]
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486
kthread+0x370/0x450 kernel/kthread.c:436
ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:klist_put+0x4d/0x1d0 lib/klist.c:212
Code: c1 ea 03 80 3c 02 00 0f 85 74 01 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b 23 49 83 e4 fe 49 8d 7c 24 58 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 43 01 00 00 4c 89 e7 4d 8b 74 24 58 e8 7c 10 0d
RSP: 0018:ffffc90000687620 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff888036142880 RCX: 0000000000000000
RDX: 000000000000000b RSI: ffffffff8bb263a5 RDI: 0000000000000058
RBP: 0000000000000001 R08: 0000000000000000 R09: fffffbfff2247f98
R10: ffffffff9123fcc3 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000001 R14: ffffffff9123fc80 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880d5cde000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff41160ff4 CR3: 000000002ccae000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess):
0: c1 ea 03 shr $0x3,%edx
3: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1)
7: 0f 85 74 01 00 00 jne 0x181
d: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
14: fc ff df
17: 4c 8b 23 mov (%rbx),%r12
1a: 49 83 e4 fe and $0xfffffffffffffffe,%r12
1e: 49 8d 7c 24 58 lea 0x58(%r12),%rdi
23: 48 89 fa mov %rdi,%rdx
26: 48 c1 ea 03 shr $0x3,%rdx
* 2a: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction
2e: 0f 85 43 01 00 00 jne 0x177
34: 4c 89 e7 mov %r12,%rdi
37: 4d 8b 74 24 58 mov 0x58(%r12),%r14
3c: e8 .byte 0xe8
3d: 7c 10 jl 0x4f
3f: 0d .byte 0xd


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

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syzbot

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12:34 AM (7 hours ago) 12:34 AM
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For archival purposes, forwarding an incoming command email to
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***

Subject: [PATCH] driver core: avoid klist_remove() on unattached knode_driver
Author: khiemtra...@gmail.com

#syz test

usb_driver_claim_interface() sets dev->driver directly and skips
device_bind_driver() when the interface is not yet registered, so the
device can reach teardown with dev->driver set but knode_driver never
added to the driver's klist_devices. __device_release_driver() then
unconditionally calls klist_remove() on the unattached node, which
dereferences a NULL klist pointer in klist_put() and crashes.

Guard the klist_remove() with klist_node_attached(), mirroring the
existing check in bus_remove_device() for knode_bus.

Reported-by: syzbot+871882...@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=87188222c77c0dbbdb4d
Signed-off-by: Nguyen Quang Le Kien <khiemtra...@gmail.com>
---
drivers/base/dd.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 60c005223..14752a5e5 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -1354,7 +1354,8 @@ static void __device_release_driver(struct device *dev, struct device *parent)
device_unbind_cleanup(dev);
device_links_driver_cleanup(dev);

- klist_remove(&dev->p->knode_driver);
+ if (klist_node_attached(&dev->p->knode_driver))
+ klist_remove(&dev->p->knode_driver);
device_pm_check_callbacks(dev);

bus_notify(dev, BUS_NOTIFY_UNBOUND_DRIVER);
--
2.34.1

Edward Adam Davis

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1:31 AM (6 hours ago) 1:31 AM
to syzbot+871882...@syzkaller.appspotmail.com, linux-...@vger.kernel.org, syzkall...@googlegroups.com
#syz test

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 60c005223844..4154b44990b2 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -1354,7 +1354,8 @@ static void __device_release_driver(struct device *dev, struct device *parent)
device_unbind_cleanup(dev);
device_links_driver_cleanup(dev);

- klist_remove(&dev->p->knode_driver);
+ if (device_is_bound(dev))

syzbot

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1:43 AM (6 hours ago) 1:43 AM
to khiemtra...@gmail.com, linux-...@vger.kernel.org, syzkall...@googlegroups.com
Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+871882...@syzkaller.appspotmail.com
Tested-by: syzbot+871882...@syzkaller.appspotmail.com

Tested on:

commit: a4ff2be3 Merge tag 'v7.3-p1' of git://git.kernel.org/p..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11c2d679580000
kernel config: https://syzkaller.appspot.com/x/.config?x=29686c02180e4e86
dashboard link: https://syzkaller.appspot.com/bug?extid=87188222c77c0dbbdb4d
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
patch: https://syzkaller.appspot.com/x/patch.diff?x=1328f815580000

Note: testing is done by a robot and is best-effort only.

syzbot

unread,
2:03 AM (5 hours ago) 2:03 AM
to ead...@qq.com, linux-...@vger.kernel.org, syzkall...@googlegroups.com
Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+871882...@syzkaller.appspotmail.com
Tested-by: syzbot+871882...@syzkaller.appspotmail.com

Tested on:

commit: a4ff2be3 Merge tag 'v7.3-p1' of git://git.kernel.org/p..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10b4f815580000
kernel config: https://syzkaller.appspot.com/x/.config?x=29686c02180e4e86
dashboard link: https://syzkaller.appspot.com/bug?extid=87188222c77c0dbbdb4d
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
patch: https://syzkaller.appspot.com/x/patch.diff?x=16faa549580000

Edward Adam Davis

unread,
2:11 AM (5 hours ago) 2:11 AM
to syzbot+871882...@syzkaller.appspotmail.com, da...@kernel.org, drive...@lists.linux.dev, gre...@linuxfoundation.org, linux-...@vger.kernel.org, linu...@vger.kernel.org, raf...@kernel.org, syzkall...@googlegroups.com
After the user writes 0 to /sys/bus/usb/drivers_autoprobe, the USB device
fails to undergo the probe process, and the user does not manually perform
a bind operation.

Consequently, the corresponding driver is not bound to the device; this
leads to the removal of `dev->p->knode_driver` during driver release upon
usb device disconnection, triggering [1].

Add a check for knode_driver before removing it.

[1]
Oops: general protection fault, probably for non-canonical address 0xdffffc000000000b: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000058-0x000000000000005f]
Call Trace:
klist_del lib/klist.c:230 [inline]
klist_remove+0x14c/0x2e0 lib/klist.c:249
__device_release_driver drivers/base/dd.c:1357 [inline]
device_release_driver_internal+0x4fb/0x620 drivers/base/dd.c:1372
bus_remove_device+0x2bc/0x560 drivers/base/bus.c:664
device_del+0x376/0x9b0 drivers/base/core.c:3961
usb_disable_device+0x367/0x810 drivers/usb/core/message.c:1478
usb_disconnect+0x2e2/0x9a0 drivers/usb/core/hub.c:2345
hub_port_connect drivers/usb/core/hub.c:5415 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5715 [inline]
port_event drivers/usb/core/hub.c:5879 [inline]
hub_event+0x1bb1/0x4420 drivers/usb/core/hub.c:5961

Fixes: 94e7b1c5ff20 ("[PATCH] Add a klist to struct device_driver for the devices bound to it.")
Tested-by: syzbot+871882...@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <ead...@qq.com>
---
drivers/base/dd.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--
2.43.0

syzbot

unread,
2:13 AM (5 hours ago) 2:13 AM
to linux-...@vger.kernel.org, syzkall...@googlegroups.com
For archival purposes, forwarding an incoming command email to
linux-...@vger.kernel.org, syzkall...@googlegroups.com.

***

Subject: [PATCH] driver core: avoid klist_remove() on unattached knode_driver
Author: khiemtra...@gmail.com

#syz test

usb_driver_claim_interface() sets dev->driver directly and skips
device_bind_driver() when the interface is not yet registered, so the
device can reach teardown with dev->driver set but knode_driver never
added to the driver's klist_devices. __device_release_driver() then
unconditionally calls klist_remove() on the unattached node, which
dereferences a NULL klist pointer in klist_put() and crashes.

Only remove the node if the device is actually bound, mirroring the
check device_is_bound() already provides for the driver core. This
matches the existing guard on knode_bus in bus_remove_device().
Signed-off-by: Nguyen Quang Le Kien <khiemtra...@gmail.com>
---
drivers/base/dd.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 60c005223..4154b4499 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -1354,7 +1354,8 @@ static void __device_release_driver(struct device *dev, struct device *parent)
device_unbind_cleanup(dev);
device_links_driver_cleanup(dev);

- klist_remove(&dev->p->knode_driver);
+ if (device_is_bound(dev))
+ klist_remove(&dev->p->knode_driver);
device_pm_check_callbacks(dev);

bus_notify(dev, BUS_NOTIFY_UNBOUND_DRIVER);
--
2.34.1

syzbot

unread,
2:34 AM (5 hours ago) 2:34 AM
to khiemtra...@gmail.com, linux-...@vger.kernel.org, syzkall...@googlegroups.com
Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+871882...@syzkaller.appspotmail.com
Tested-by: syzbot+871882...@syzkaller.appspotmail.com

Tested on:

commit: a4ff2be3 Merge tag 'v7.3-p1' of git://git.kernel.org/p..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=168ad679580000
kernel config: https://syzkaller.appspot.com/x/.config?x=29686c02180e4e86
dashboard link: https://syzkaller.appspot.com/bug?extid=87188222c77c0dbbdb4d
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
patch: https://syzkaller.appspot.com/x/patch.diff?x=16dcee79580000
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