Bug#690505: broken usb device breaks direct i/o even to non-usb drives
 

reassign 690504 src:linux
forcemerge 690505 690504
quit

Hi Ben,

Ben Hutchings wrote:
> mail user wrote:

>> plugging in a fake (128 that later turned out to be just 2Gb) flashdrive
>> in the usb port, dd it to /dev/null, ctrl-c, dd zeroes to it, ctrl-c,
>> dd unresponsive to ctrl-c
[...]
>> then
>> rmmod -f usb-storage
>>
>> then
>> unplug the flashdrive
[...]
>> [...] BUG: unable to handle kernel paging request at ffffffffa05b9020
[...]
> You cannot expect the kernel to work after forcing module removal.

Agreed, but isn't the initial uninterruptible dd hang a (hardware or
software) bug?

Thanks,
Jonathan


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Bug#690505: broken usb device breaks direct i/o even to non-usb drives
 

On Sun, 2012-10-14 at 19:03 -0700, Jonathan Nieder wrote:
> reassign 690504 src:linux
> forcemerge 690505 690504
> quit
>
> Hi Ben,
>
> Ben Hutchings wrote:
> > mail user wrote:
>
> >> plugging in a fake (128 that later turned out to be just 2Gb) flashdrive
> >> in the usb port, dd it to /dev/null, ctrl-c, dd zeroes to it, ctrl-c,
> >> dd unresponsive to ctrl-c
> [...]
> >> then
> >> rmmod -f usb-storage
> >>
> >> then
> >> unplug the flashdrive
> [...]
> >> [...] BUG: unable to handle kernel paging request at ffffffffa05b9020
> [...]
> > You cannot expect the kernel to work after forcing module removal.
>
> Agreed, but isn't the initial uninterruptible dd hang a (hardware or
> software) bug?

We know the external hardware is (deliberately) broken. Since the
result is not a privilege escalation, I don't see any reason to care
about it.

Ben.

--
Ben Hutchings
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