Date: Sat, 28 Sep 2013 08:30:06 +0200 From: Hannes Frederic Sowa <hannes@...essinduktion.org> To: oss-security@...ts.openwall.com Cc: dvyukov@...gle.com Subject: linux kernel memory corruption with ipv6 udp offloading Hi! I guess the following patch might be worth a CVE: | [PATCH] ipv6: udp packets following an UFO enqueued packet need also be handled by UFO | | In the following scenario the socket is corked: | If the first UDP packet is larger then the mtu we try to append it to the | write queue via ip6_ufo_append_data. A following packet, which is smaller | than the mtu would be appended to the already queued up gso-skb via | plain ip6_append_data. This causes random memory corruptions. | | In ip6_ufo_append_data we also have to be careful to not queue up the | same skb multiple times. So setup the gso frame only when no first skb | is available. | | This also fixes a shortcoming where we add the current packet's length to | cork->length but return early because of a packet > mtu with dontfrag set | (instead of sutracting it again). | | Found with trinity. While writing a reproducer to test this patch, I have seen silent memory corruption (which later manifests as e.g. a panic or hangs on shutdown) and oopses. It has been reported to netdev by Dmitry Vyukov <dvyukov@...gle.com> and was found with the AddressSanitizer for the kernel and trinity. The patch is queued up for stable: http://patchwork.ozlabs.org/patch/276835/ and is already committed to linux-net: https://git.kernel.org/cgit/linux/kernel/git/davem/net.git/commit/?id=2811ebac2521ceac84f2bdae402455baa6a7fb47 I guess the erroneous behaviour was introduced here: | git describe --contains e89e9cf539a28df7d0eb1d0a545368e9920b34ac | v2.6.15-rc1~731^2~31 The reproducers are available on request.  https://code.google.com/p/address-sanitizer/wiki/AddressSanitizerForKernel Thanks, Hannes
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