linux-kernel - Re: [syzbot] INFO: task hung in usb_get

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Date:   Sat, 12 Feb 2022 23:40:13 -0800
From:   syzbot <syzbot+31ae6d17d115e980fd14@...kaller.appspotmail.com>
To:     brouer@...hat.com, gregkh@...uxfoundation.org, hdanton@...a.com,
        linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
        skhan@...uxfoundation.org, stern@...land.harvard.edu,
        syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] INFO: task hung in usb_get_descriptor

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: null-ptr-deref Write in vhci_shutdown_connection

==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_write include/linux/instrumented.h:71 [inline]
BUG: KASAN: null-ptr-deref in atomic_fetch_add_relaxed include/asm-generic/atomic-instrumented.h:142 [inline]
BUG: KASAN: null-ptr-deref in refcount_add include/linux/refcount.h:201 [inline]
BUG: KASAN: null-ptr-deref in refcount_inc include/linux/refcount.h:241 [inline]
BUG: KASAN: null-ptr-deref in get_task_struct include/linux/sched/task.h:104 [inline]
BUG: KASAN: null-ptr-deref in kthread_stop+0x90/0x810 kernel/kthread.c:591
Write of size 4 at addr 000000000000001c by task kworker/u4:4/186

CPU: 0 PID: 186 Comm: kworker/u4:4 Not tainted 5.9.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: usbip_event event_handler
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x107/0x16e lib/dump_stack.c:118
 __kasan_report mm/kasan/report.c:517 [inline]
 kasan_report.cold+0x5/0x37 mm/kasan/report.c:530
 check_memory_region_inline mm/kasan/generic.c:186 [inline]
 check_memory_region+0x13d/0x180 mm/kasan/generic.c:192
 instrument_atomic_write include/linux/instrumented.h:71 [inline]
 atomic_fetch_add_relaxed include/asm-generic/atomic-instrumented.h:142 [inline]
 refcount_add include/linux/refcount.h:201 [inline]
 refcount_inc include/linux/refcount.h:241 [inline]
 get_task_struct include/linux/sched/task.h:104 [inline]
 kthread_stop+0x90/0x810 kernel/kthread.c:591
 vhci_shutdown_connection+0x17f/0x360 drivers/usb/usbip/vhci_hcd.c:1015
 event_handler+0x1f0/0x4f0 drivers/usb/usbip/usbip_event.c:78
 process_one_work+0x86c/0x16a0 kernel/workqueue.c:2269
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
 kthread+0x3b5/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
==================================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 186 Comm: kworker/u4:4 Tainted: G    B             5.9.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: usbip_event event_handler
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x107/0x16e lib/dump_stack.c:118
 panic+0x393/0x7d3 kernel/panic.c:231
 end_report+0x4d/0x53 mm/kasan/report.c:104
 __kasan_report mm/kasan/report.c:520 [inline]
 kasan_report.cold+0xd/0x37 mm/kasan/report.c:530
 check_memory_region_inline mm/kasan/generic.c:186 [inline]
 check_memory_region+0x13d/0x180 mm/kasan/generic.c:192
 instrument_atomic_write include/linux/instrumented.h:71 [inline]
 atomic_fetch_add_relaxed include/asm-generic/atomic-instrumented.h:142 [inline]
 refcount_add include/linux/refcount.h:201 [inline]
 refcount_inc include/linux/refcount.h:241 [inline]
 get_task_struct include/linux/sched/task.h:104 [inline]
 kthread_stop+0x90/0x810 kernel/kthread.c:591
 vhci_shutdown_connection+0x17f/0x360 drivers/usb/usbip/vhci_hcd.c:1015
 event_handler+0x1f0/0x4f0 drivers/usb/usbip/usbip_event.c:78
 process_one_work+0x86c/0x16a0 kernel/workqueue.c:2269
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
 kthread+0x3b5/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
Kernel Offset: disabled
Rebooting in 86400 seconds..

Tested on:

commit:         d3d45f82 Merge tag 'pinctrl-v5.9-2' of git://git.kerne..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
console output: https://syzkaller.appspot.com/x/log.txt?x=125b4faa700000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c4f7c05cb42b5045
dashboard link: https://syzkaller.appspot.com/bug?extid=31ae6d17d115e980fd14
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1359552c700000