From: David Miller <davem@davemloft.net>
To: ast@plumgrid.com
Cc: daniel@iogearbox.net, hannes@stressinduktion.org, netdev@vger.kernel.org
Subject: Re: [PATCH net] bpf: fix two bugs in verification logic when accessing 'ctx' pointer
Date: Thu, 16 Apr 2015 14:10:15 -0400 (EDT) [thread overview]
Message-ID: <20150416.141015.2085337707033100619.davem@davemloft.net> (raw)
In-Reply-To: <1429139973-5473-1-git-send-email-ast@plumgrid.com>
From: Alexei Starovoitov <ast@plumgrid.com>
Date: Wed, 15 Apr 2015 16:19:33 -0700
> 1.
> first bug is a silly mistake. It broke tracing examples and prevented
> simple bpf programs from loading.
...
> 2.
> second bug is more subtle.
> If malicious code is using the same dest register as source register,
> the checks designed to prevent the same instruction to be used with different
> pointer types will fail to trigger, since we were assigning src_reg_type
> when it was already overwritten by check_mem_access().
> The fix is trivial. Just move line:
> src_reg_type = regs[insn->src_reg].type;
> before check_mem_access().
> Add new 'access skb fields bad4' test to check this case.
>
> Fixes: 9bac3d6d548e ("bpf: allow extended BPF programs access skb fields")
> Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Applied, thank you.
prev parent reply other threads:[~2015-04-16 18:10 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-15 23:19 [PATCH net] bpf: fix two bugs in verification logic when accessing 'ctx' pointer Alexei Starovoitov
2015-04-16 18:10 ` David Miller [this message]
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