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From: Eric Dumazet <eric.dumazet@gmail.com>
To: Greg Hackmann <ghackmann@google.com>,
	Steffen Klassert <steffen.klassert@secunet.com>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	"David S. Miller" <davem@davemloft.net>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] net: xfrm: use preempt-safe this_cpu_read() in ipcomp_alloc_tfms()
Date: Wed, 07 Mar 2018 12:21:21 -0800	[thread overview]
Message-ID: <1520454081.109662.54.camel@gmail.com> (raw)
In-Reply-To: <20180307192416.233202-1-ghackmann@google.com>

On Wed, 2018-03-07 at 11:24 -0800, Greg Hackmann wrote:
> f7c83bcbfaf5 ("net: xfrm: use __this_cpu_read per-cpu helper") added
> a
> __this_cpu_read() call inside ipcomp_alloc_tfms().  Since this call
> was
> introduced, the rules around per-cpu accessors have been tightened
> and
> __this_cpu_read() cannot be used in a preemptible context.
> 
> syzkaller reported this leading to the following kernel BUG while
> fuzzing sendmsg:
> 
> 
> Cc: stable@vger.kernel.org

Hi Greg, thanks for this patch.

1) Please read Documentation/networking/netdev-FAQ.txt
around line 133

2) If you believe this needs to be backported, you must provide
a Fixes: tag to clearly identify commit that changed the behavior.

Otherwise dozens of stable teams will have to figure out by themselves,
wasting precious time.

Thanks.

  reply	other threads:[~2018-03-07 20:21 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-07 19:24 [PATCH] net: xfrm: use preempt-safe this_cpu_read() in ipcomp_alloc_tfms() Greg Hackmann
2018-03-07 20:21 ` Eric Dumazet [this message]
2018-03-07 20:50   ` Greg Hackmann
2018-03-08  7:33 ` Herbert Xu
2018-03-08 16:31   ` Eric Dumazet
2018-03-08 18:40     ` Herbert Xu

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