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From: Florian Westphal <fw@strlen.de>
To: David Miller <davem@davemloft.net>
Cc: fw@strlen.de, netdev@vger.kernel.org
Subject: Re: [PATCH net-next] netlink: make getters tolerate NULL nla arg
Date: Sun, 19 Jan 2020 13:32:39 +0100	[thread overview]
Message-ID: <20200119123239.GB795@breakpoint.cc> (raw)
In-Reply-To: <20200117.040849.2032549448991143345.davem@davemloft.net>

David Miller <davem@davemloft.net> wrote:
> From: Florian Westphal <fw@strlen.de>
> Date: Thu, 16 Jan 2020 15:55:22 +0100
> 
> > One recurring bug pattern triggered by syzbot is NULL dereference in
> > netlink code paths due to a missing "tb[NL_ARG_FOO] != NULL" test.
> > 
> > At least some of these missing checks would not have crashed the kernel if
> > the various nla_get_XXX helpers would return 0 in case of missing arg.
> > 
> > Make the helpers return 0 instead of crashing when a null nla is provided.
> > Even with allyesconfig the .text increase is only about 350 bytes.
> > 
> > Signed-off-by: Florian Westphal <fw@strlen.de>
> 
> Sorry, I think it's better to find out when code is trying to access
> attributes without verifying that they are even supplied.

Less than 24 hours after I saw this patch marked rejected syzbot
reported another incarnation of this pattern.

Would you consider a v2 with a WARN_ON_ONCE() added (and the
buildbot warning resolved)?

Thanks.

  reply	other threads:[~2020-01-19 12:34 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-16 14:55 [PATCH net-next] netlink: make getters tolerate NULL nla arg Florian Westphal
2020-01-16 15:19 ` Toke Høiland-Jørgensen
2020-01-16 16:04   ` Florian Westphal
2020-01-16 16:23     ` Toke Høiland-Jørgensen
2020-01-17 10:39       ` Florian Westphal
2020-01-17 16:26         ` Toke Høiland-Jørgensen
2020-01-17 12:08 ` David Miller
2020-01-19 12:32   ` Florian Westphal [this message]
2020-01-19 14:08     ` David Miller
2020-01-17 22:28 ` kbuild test robot
2020-01-17 22:28   ` kbuild test robot
2020-01-18  9:40 ` kbuild test robot
2020-01-18  9:40   ` kbuild test robot
2020-01-24 15:47 ` kbuild test robot
2020-01-24 15:47   ` kbuild test robot

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