Re: [PATCH] __bitmap_parselist: fix bug in empty string handling

[Chris Metcalf]

> On Apr 20, 2015, at 1:17 PM, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> 
>> On Fri, 17 Apr 2015 14:00:04 -0400 Chris Metcalf <cmetcalf@xxxxxxxxxx> wrote:
>> 
>> bitmap_parselist("", &mask, nmaskbits) will erroneously set bit
>> zero in the mask.  The same bug is visible in cpumask_parselist()
>> since it is layered on top of the bitmask code, e.g. if you boot with
>> "isolcpus=", you will actually end up with cpu zero isolated.
>> 
>> The bug was introduced in commit 4b060420a596 ("bitmap, irq: add
>> smp_affinity_list interface to /proc/irq") when bitmap_parselist()
>> was generalized to support userspace as well as kernelspace.
>> 
>> Signed-off-by: Chris Metcalf <cmetcalf@xxxxxxxxxx>
>> Cc: stable@xxxxxxxxxxxxxxx
> 
> I don't think we need to backport a fix for a 4 year old bug which has
> very minor consequences.  Am I wrong?

I don't have a strong feeling on this one. My guess is it's trivial to backport but also very low impact so either way is pretty reasonable.

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