lkml.org 
[lkml]   [2023]   [Jan]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRE: [PATCH net, 2/2] net: mana: Fix accessing freed irq affinity_hint
Date


> -----Original Message-----
> From: Michael Kelley (LINUX) <mikelley@microsoft.com>
> Sent: Sunday, January 29, 2023 9:27 AM
> To: Haiyang Zhang <haiyangz@microsoft.com>; linux-hyperv@vger.kernel.org;
> netdev@vger.kernel.org
> Cc: Haiyang Zhang <haiyangz@microsoft.com>; Dexuan Cui
> <decui@microsoft.com>; KY Srinivasan <kys@microsoft.com>; Paul Rosswurm
> <paulros@microsoft.com>; olaf@aepfle.de; vkuznets@redhat.com;
> davem@davemloft.net; linux-kernel@vger.kernel.org; stable@vger.kernel.org
> Subject: RE: [PATCH net, 2/2] net: mana: Fix accessing freed irq affinity_hint
>
> From: LKML haiyangz <lkmlhyz@microsoft.com> On Behalf Of Haiyang Zhang
> Sent: Thursday, January 26, 2023 1:05 PM
> >
> > After calling irq_set_affinity_and_hint(), the cpumask pointer is
> > saved in desc->affinity_hint, and will be used later when reading
> > /proc/irq/<num>/affinity_hint. So the cpumask variable needs to be
> > allocated per irq, and available until freeing the irq. Otherwise,
> > we are accessing freed memory when reading the affinity_hint file.
> >
> > To fix the bug, allocate the cpumask per irq, and free it just
> > before freeing the irq.
>
> Since the cpumask being passed to irq_set_affinity_and_hint()
> always contains exactly one CPU, the code can be considerably
> simplified by using the pre-calculated and persistent masks
> available as cpumask_of(cpu). All allocation of cpumasks in this
> code goes away, and you can set the affinity_hint to NULL in the
> cleanup and remove paths without having to free any masks.
>
Great idea!
Will update the patch accordingly.

- Haiyang

\
 
 \ /
  Last update: 2023-03-27 00:01    [W:0.091 / U:0.032 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site