Date:   Wed, 5 May 2021 14:38:50 -0700
From:   SyzScope <syzscope@...il.com>
To:     Andrey Konovalov <andreyknvl@...gle.com>,
        syzbot <syzbot+76929be61691e7b3904b@...kaller.appspotmail.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, linux-media@...r.kernel.org,
        USB list <linux-usb@...r.kernel.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        syzkaller-bugs <syzkaller-bugs@...glegroups.com>
Subject: Re: WARNING in em28xx_init_extension

Hi,

This is SyzScope, a research project that aims to reveal high-risk 
primitives from a seemingly low-risk bug (UAF/OOB read, WARNING, BUG, etc.).

We are currently testing seemingly low-risk bugs on syzbot's open 
section(https://syzkaller.appspot.com/upstream), and try to reach out to 
kernel developers if SyzScope discovers any high-risk primitives.

Regrading the bug "BUG: corrupted list in em28xx_init_extension", it 
seems that this bug is still missing a valid patch.

SyzScope reports 4 memory write primitives from this bug.

The detailed comments can be found at 
https://sites.google.com/view/syzscope/bug-corrupted-list-in-em28xx_init_extension

Please let us know if SyzScope indeed helps, and any suggestions/feedback.

On 3/9/2020 8:24 AM, Andrey Konovalov wrote:
> On Fri, Sep 27, 2019 at 10:49 PM syzbot
> <syzbot+76929be61691e7b3904b@...kaller.appspotmail.com> wrote:
>> Hello,
>>
>> syzbot found the following crash on:
>>
>> HEAD commit:    2994c077 usb-fuzzer: main usb gadget fuzzer driver
>> git tree:       https://github.com/google/kasan.git usb-fuzzer
>> console output: https://syzkaller.appspot.com/x/log.txt?x=171c4be3600000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=69ddefac6929256a
>> dashboard link: https://syzkaller.appspot.com/bug?extid=76929be61691e7b3904b
>> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
>> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=137d73bd600000
>> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14f0c8cb600000
>>
>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>> Reported-by: syzbot+76929be61691e7b3904b@...kaller.appspotmail.com
>>
>> em28xx 1-1:0.221: Audio interface 221 found (Vendor Class)
>> em28xx 1-1:0.221: unknown em28xx chip ID (0)
>> em28xx 1-1:0.221: Config register raw data: 0xfffffffb
>> em28xx 1-1:0.221: AC97 chip type couldn't be determined
>> em28xx 1-1:0.221: No AC97 audio processor
>> ------------[ cut here ]------------
>> list_add corruption. prev->next should be next (ffffffff87779de0), but was
>> ffffffff8352fdcc. (prev=ffff8881d2ecc240).
>> WARNING: CPU: 1 PID: 83 at lib/list_debug.c:26 __list_add_valid+0x99/0xf0
>> lib/list_debug.c:26
>> Kernel panic - not syncing: panic_on_warn set ...
>> CPU: 1 PID: 83 Comm: kworker/1:2 Not tainted 5.3.0+ #0
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
>> Google 01/01/2011
>> Workqueue: usb_hub_wq hub_event
>> Call Trace:
>>    __dump_stack lib/dump_stack.c:77 [inline]
>>    dump_stack+0xca/0x13e lib/dump_stack.c:113
>>    panic+0x2a3/0x6da kernel/panic.c:219
>>    __warn.cold+0x20/0x4a kernel/panic.c:576
>>    report_bug+0x262/0x2a0 lib/bug.c:186
>>    fixup_bug arch/x86/kernel/traps.c:179 [inline]
>>    fixup_bug arch/x86/kernel/traps.c:174 [inline]
>>    do_error_trap+0x12b/0x1e0 arch/x86/kernel/traps.c:272
>>    do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:291
>>    invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1028
>> RIP: 0010:__list_add_valid+0x99/0xf0 lib/list_debug.c:26
>> Code: 48 c7 c7 60 06 db 85 e8 2a 7a 30 ff 0f 0b 48 83 c4 08 31 c0 5d 41 5c
>> c3 48 89 f1 48 c7 c7 20 07 db 85 4c 89 e6 e8 0c 7a 30 ff <0f> 0b 31 c0 eb
>> c5 48 89 f2 4c 89 e1 48 89 ee 48 c7 c7 a0 07 db 85
>> RSP: 0018:ffff8881d93cf120 EFLAGS: 00010286
>> RAX: 0000000000000000 RBX: ffff8881d2810120 RCX: 0000000000000000
>> RDX: 0000000000000000 RSI: ffffffff8128d3fd RDI: ffffed103b279e16
>> RBP: ffff8881d2810240 R08: ffff8881d92a3000 R09: fffffbfff11f45af
>> R10: fffffbfff11f45ae R11: ffffffff88fa2d77 R12: ffffffff87779de0
>> R13: ffff8881d2810000 R14: ffff8881d281012c R15: ffff8881d2c84400
>>    __list_add include/linux/list.h:60 [inline]
>>    list_add_tail include/linux/list.h:93 [inline]
>>    em28xx_init_extension+0x44/0x1f0
>> drivers/media/usb/em28xx/em28xx-core.c:1125
>>    em28xx_init_dev.isra.0+0xa7b/0x15d8
>> drivers/media/usb/em28xx/em28xx-cards.c:3520
>>    em28xx_usb_probe.cold+0xcac/0x2516
>> drivers/media/usb/em28xx/em28xx-cards.c:3869
>>    usb_probe_interface+0x305/0x7a0 drivers/usb/core/driver.c:361
>>    really_probe+0x281/0x6d0 drivers/base/dd.c:548
>>    driver_probe_device+0x104/0x210 drivers/base/dd.c:721
>>    __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:828
>>    bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:430
>>    __device_attach+0x217/0x360 drivers/base/dd.c:894
>>    bus_probe_device+0x1e4/0x290 drivers/base/bus.c:490
>>    device_add+0xae6/0x16f0 drivers/base/core.c:2201
>>    usb_set_configuration+0xdf6/0x1670 drivers/usb/core/message.c:2023
>>    generic_probe+0x9d/0xd5 drivers/usb/core/generic.c:210
>>    usb_probe_device+0x99/0x100 drivers/usb/core/driver.c:266
>>    really_probe+0x281/0x6d0 drivers/base/dd.c:548
>>    driver_probe_device+0x104/0x210 drivers/base/dd.c:721
>>    __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:828
>>    bus_for_each_drv+0x162/0x1e0 drivers/base/bus.c:430
>>    __device_attach+0x217/0x360 drivers/base/dd.c:894
>>    bus_probe_device+0x1e4/0x290 drivers/base/bus.c:490
>>    device_add+0xae6/0x16f0 drivers/base/core.c:2201
>>    usb_new_device.cold+0x6a4/0xe79 drivers/usb/core/hub.c:2536
>>    hub_port_connect drivers/usb/core/hub.c:5098 [inline]
>>    hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
>>    port_event drivers/usb/core/hub.c:5359 [inline]
>>    hub_event+0x1b5c/0x3640 drivers/usb/core/hub.c:5441
>>    process_one_work+0x92b/0x1530 kernel/workqueue.c:2269
>>    process_scheduled_works kernel/workqueue.c:2331 [inline]
>>    worker_thread+0x7ab/0xe20 kernel/workqueue.c:2417
>>    kthread+0x318/0x420 kernel/kthread.c:255
>>    ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
>> Kernel Offset: disabled
>> Rebooting in 86400 seconds..
>>
>>
>> ---
>> This bug 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 syzkaller@...glegroups.com.
>>
>> syzbot will keep track of this bug report. See:
>> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>> syzbot can test patches for this bug, for details see:
>> https://goo.gl/tpsmEJ#testing-patches
> #syz dup: BUG: corrupted list in em28xx_init_extension
>

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