netdev - Re: [PATCH net] bpf: fix two bugs in verification logic when accessing 'ctx' pointer

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Thu, 16 Apr 2015 14:10:15 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	ast@...mgrid.com
Cc:	daniel@...earbox.net, hannes@...essinduktion.org,
	netdev@...r.kernel.org
Subject: Re: [PATCH net] bpf: fix two bugs in verification logic when
 accessing 'ctx' pointer

From: Alexei Starovoitov <ast@...mgrid.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@...mgrid.com>

Applied, thank you.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html