Re: [BUG] usb: dwc3: Kernel NULL pointer dereference in dwc3_remove()

[Alexandru Elisei]

Hi Greg,

On 6/3/21 12:40 PM, Greg Kroah-Hartman wrote:
> On Thu, Jun 03, 2021 at 11:41:45AM +0100, Alexandru Elisei wrote:
>> Hello Felipe,
>>
>> Thank you for having a look!
>>
>> On 6/3/21 7:30 AM, Felipe Balbi wrote:
>>> Hi,
>>>
>>> Alexandru Elisei <alexandru.elisei@xxxxxxx> writes:
>>>> I've been seeing the following panic when shutting down my rockpro64:
>>>>
>>>> [�� 21.459064] xhci-hcd xhci-hcd.0.auto: USB bus 5 deregistered
>>>> [�� 21.683077] Unable to handle kernel NULL pointer dereference at virtual address
>>>> 00000000000000a0
>>>> [�� 21.683858] Mem abort info:
>>>> [�� 21.684104]�� ESR = 0x96000004
>>>> [�� 21.684375]�� EC = 0x25: DABT (current EL), IL = 32 bits
>>>> [�� 21.684841]�� SET = 0, FnV = 0
>>>> [�� 21.685111]�� EA = 0, S1PTW = 0
>>>> [�� 21.685389] Data abort info:
>>>> [�� 21.685644]�� ISV = 0, ISS = 0x00000004
>>>> [�� 21.686024]�� CM = 0, WnR = 0
>>>> [�� 21.686288] user pgtable: 4k pages, 48-bit VAs, pgdp=000000000757a000
>>>> [�� 21.686853] [00000000000000a0] pgd=0000000000000000, p4d=0000000000000000
>>>> [�� 21.687452] Internal error: Oops: 96000004EEMPT SMP
>>>> [�� 21.687941] Modules linked in:
>>>> [�� 21.688214] CPU: 4 PID: 1 Comm: shutdown Not tainted
>>>> 5.12.0-rc7-00262-g568262bf5492 #33
>>>> [�� 21.688915] Hardware name: Pine64 RockPro64 v2.0 (DT)
>>>> [�� 21.689357] pstate: 60000005 (nZCv daif -PAN -UAO -TCO BTYPE=--)
>>>> [�� 21.689884] pc : down_read_interruptible+0xec/0x200
>>>> [�� 21.690321] lr : simple_recursive_removal+0x48/0x280
>>>> [�� 21.690761] sp : ffff800011f4b940
>>>> [�� 21.691053] x29: ffff800011f4b940 x28: ffff000000809b40
>>>> [�� 21.691522] x27: ffff000000809b98 x26: ffff8000114f5170
>>>> [�� 21.691990] x25: 00000000000000a0 x24: ffff800011e84030
>>>> [�� 21.692459] x23: 0000000000000080 x22: 0000000000000000
>>>> [�� 21.692927] x21: ffff800011ecaa5c x20: ffff800011ecaa60
>>>> [�� 21.693395] x19: ffff000000809b40 x18: ffffffffffffffff
>>>> [�� 21.693863] x17: 0000000000000000 x16: 0000000000000000
>>>> [�� 21.694331] x15: ffff800091f4ba6d x14: 0000000000000004
>>>> [�� 21.694799] x13: 0000000000000000 x12: 0000000000000020
>>>> [�� 21.695267] x11: 0101010101010101 x10: 7f7f7f7f7f7f7f7f
>>>> [�� 21.695735] x9 : 6f6c746364716e62 x8 : 7f7f7f7f7f7f7f7f
>>>> [�� 21.696203] x7 : fefefeff6364626d x6 : 0000000000001bd8
>>>> [�� 21.696671] x5 : 0000000000000000 x4 : 0000000000000000
>>>> [�� 21.697138] x3 : 00000000000000a0 x2 : 0000000000000001
>>>> [�� 21.697606] x1 : 0000000000000000 x0 : 00000000000000a0
>>>> [�� 21.698075] Call trace:
>>>> [�� 21.698291]� down_read_interruptible+0xec/0x200
>>>> [�� 21.698690]� debugfs_remove+0x60/0x84
>>>> [�� 21.699016]� dwc3_debugfs_exit+0x1c/0x6c
>>>> [�� 21.699363]� dwc3_remove+0x34/0x1a0
>>>> [�� 21.699672]� platform_remove+0x28/0x60
>>>> [�� 21.700005]� __device_release_driver+0x188/0x230
>>>> [�� 21.700414]� device_release_driver+0x2c/0x44
>>>> [�� 21.700791]� bus_remove_device+0x124/0x130
>>>> [�� 21.701154]� device_del+0x168/0x420
>>>> [�� 21.701462]� platform_device_del.part.0+0x1c/0x90
>>>> [�� 21.701877]� platform_device_unregister+0x28/0x44
>>>> [�� 21.702291]� of_platform_device_destroy+0xe8/0x100
>>>> [�� 21.702716]� device_for_each_child_reverse+0x64/0xb4
>>>> [�� 21.703153]� of_platform_depopulate+0x40/0x84
>>>> [�� 21.703538]� __dwc3_of_simple_teardown+0x20/0xd4
>>>> [�� 21.703945]� dwc3_of_simple_shutdown+0x14/0x20
>>>> [�� 21.704337]� platform_shutdown+0x28/0x40
>>>> [�� 21.704683]� device_shutdown+0x158/0x330
>>>> [�� 21.705029]� kernel_power_off+0x38/0x7c
>>>> [�� 21.705372]� __do_sys_reboot+0x16c/0x2a0
>>>> [�� 21.705719]� __arm64_sys_reboot+0x28/0x34
>>>> [�� 21.706074]� el0_svc_common.constprop.0+0x60/0x120
>>>> [�� 21.706499]� do_el0_svc+0x28/0x94
>>>> [�� 21.706794]� el0_svc+0x2c/0x54
>>>> [�� 21.707067]� el0_sync_handler+0xa4/0x130
>>>> [�� 21.707414]� el0_sync+0x170/0x180
>>>> [�� 21.707711] Code: c8047c62 35ffff84 17fffe5f f9800071 (c85ffc60)
>>>> [�� 21.708250] ---[ end trace 5ae08147542eb468 ]---
>>>> [�� 21.708667] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
>>>> [�� 21.709456] Kernel Offset: disabled
>>>> [�� 21.709762] CPU features: 0x00240022,2100600c
>>>> [�� 21.710146] Memory Limit: 2048 MB
>>>> [�� 21.710443] ---[ end Kernel panic - not syncing: Attempted to kill init!
>>>> exitcode=0x0000000b ]---
>>>>
>>>> I've been able to bisect the panic and the offending commit is 568262bf5492 ("usb:
>>>> dwc3: core: Add shutdown callback for dwc3"). I can provide more diagnostic
>>>> information if needed and I can help test the fix.
>>> if you simply revert that commit in HEAD, does the problem really go
>>> away?
>> Kernel built from commit 324c92e5e0ee, which is the kernel tip today, the panic is
>> there. Reverting the offending commit, 568262bf5492, makes the panic disappear.
> Want to send a revert so I can take it now?

I can send a revert, but Felipe was asking Sandeep (the commit author) for a fix,
so I'll leave it up to Felipe to decide how to proceed.

Thanks,

Alex