linux-kernel - Re: [01/34] ipv4: udp: fix short packet and bad checksum logging

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Message-ID: <87zkzoqwz8.fsf@nemi.mork.no>
Date:	Tue, 25 May 2010 09:08:59 +0200
From:	Bjørn Mork <bjorn@...k.no>
To:	Greg KH <gregkh@...e.de>
Cc:	linux-kernel@...r.kernel.org, stable@...nel.org,
	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Eric Dumazet <eric.dumazet@...il.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: Re: [01/34] ipv4: udp: fix short packet and bad checksum logging

Greg KH <gregkh@...e.de> writes:

> 2.6.34-stable review patch.  If anyone has any objections, please let us know.
>
> ------------------
>
> From: Bjørn Mork <bjorn@...k.no>
>
> commit ccc2d97cb7c798e785c9f198de243e2b59f7073b upstream.

This is already in 2.6.34 AFAIK.



Bjørn

> commit 2783ef23 moved the initialisation of saddr and daddr after
> pskb_may_pull() to avoid a potential data corruption.  Unfortunately
> also placing it after the short packet and bad checksum error paths,
> where these variables are used for logging.  The result is bogus
> output like
>
> [92238.389505] UDP: short packet: From 2.0.0.0:65535 23715/178 to 0.0.0.0:65535
>
> Moving the saddr and daddr initialisation above the error paths, while still
> keeping it after the pskb_may_pull() to keep the fix from commit 2783ef23.
>
> Signed-off-by: Bjørn Mork <bjorn@...k.no>
> Acked-by: Eric Dumazet <eric.dumazet@...il.com>
> Signed-off-by: David S. Miller <davem@...emloft.net>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
>
> ---
>  net/ipv4/udp.c |    6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> --- a/net/ipv4/udp.c
> +++ b/net/ipv4/udp.c
> @@ -1292,6 +1292,9 @@ int __udp4_lib_rcv(struct sk_buff *skb,
>  
>  	uh   = udp_hdr(skb);
>  	ulen = ntohs(uh->len);
> +	saddr = ip_hdr(skb)->saddr;
> +	daddr = ip_hdr(skb)->daddr;
> +
>  	if (ulen > skb->len)
>  		goto short_packet;
>  
> @@ -1305,9 +1308,6 @@ int __udp4_lib_rcv(struct sk_buff *skb,
>  	if (udp4_csum_init(skb, uh, proto))
>  		goto csum_error;
>  
> -	saddr = ip_hdr(skb)->saddr;
> -	daddr = ip_hdr(skb)->daddr;
> -
>  	if (rt->rt_flags & (RTCF_BROADCAST|RTCF_MULTICAST))
>  		return __udp4_lib_mcast_deliver(net, skb, uh,
>  				saddr, daddr, udptable);
--
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