netdev - Re: [PATCH] net: fix wrong skb_get() usage / crash in IGMP/MLD parsing code

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]

Message-Id: <20150813.171101.925018652514860039.davem@davemloft.net>
Date:	Thu, 13 Aug 2015 17:11:01 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	linus.luessing@...3.blue
Cc:	netdev@...r.kernel.org, bridge@...ts.linux-foundation.org,
	linux-kernel@...r.kernel.org, stephen@...workplumber.org,
	herbert@...dor.apana.org.au, bblanco@...mgrid.com,
	alexei.starovoitov@...il.com
Subject: Re: [PATCH] net: fix wrong skb_get() usage / crash in IGMP/MLD
 parsing code

From: Linus Lüssing <linus.luessing@...3.blue>
Date: Thu, 13 Aug 2015 05:54:07 +0200

> The recent refactoring of the IGMP and MLD parsing code into
> ipv6_mc_check_mld() / ip_mc_check_igmp() introduced a potential crash /
> BUG() invocation for bridges:
> 
> I wrongly assumed that skb_get() could be used as a simple reference
> counter for an skb which is not the case. skb_get() bears additional
> semantics, a user count. This leads to a BUG() invocation in
> pskb_expand_head() / kernel panic if pskb_may_pull() is called on an skb
> with a user count greater than one - unfortunately the refactoring did
> just that.
> 
> Fixing this by removing the skb_get() call and changing the API: The
> caller of ipv6_mc_check_mld() / ip_mc_check_igmp() now needs to
> additionally check whether the returned skb_trimmed is a clone.
> 
> Fixes: 9afd85c9e455 ("net: Export IGMP/MLD message validation code")
> Reported-by: Brenden Blanco <bblanco@...mgrid.com>
> Signed-off-by: Linus Lüssing <linus.luessing@...3.blue>

Applied, thanks.
--
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