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Date: Mon, 06 Jun 2011 22:24:16 -0700 (PDT) From: David Miller <davem@...emloft.net> To: eric.dumazet@...il.com Cc: netdev@...r.kernel.org, kaber@...sh.net Subject: Re: [PATCH] af_packet: prevent information leak From: Eric Dumazet <eric.dumazet@...il.com> Date: Tue, 07 Jun 2011 07:02:19 +0200 > In 2.6.27, commit 393e52e33c6c2 (packet: deliver VLAN TCI to userspace) > added a small information leak. > > Add padding field and make sure its zeroed before copy to user. > > Signed-off-by: Eric Dumazet <eric.dumazet@...il.com> > CC: Patrick McHardy <kaber@...sh.net> I fear this will change the size of these structures on some weird architecture. Doesn't ARM, for example, have weird rules wrt. alignment and structure sizing when "smaller than word" elements are involved? That's why we need __packed on: struct nd_opt_hdr { __u8 nd_opt_type; __u8 nd_opt_len; } __packed; for example. Probably safe to just do a memset of the tail, and the constant length will evaluate to zero on these weird platforms. On others, where the padding does matter, the memset will emit the same code as your new assignments do. -- 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
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