Attachment 14446 Details for Bug 13588 – Patch for 4.9

[patch] Patch for 4.9

0001-ctdb-common-Fix-aliasing-issue-in-IPv6-checksum.patch (text/plain), 2.08 KB, created by Martin Schwenke on 2018-08-26 10:34:04 UTC

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Creator: Martin Schwenke

Created: 2018-08-26 10:34:04 UTC

Size: 2.08 KB

patch

obsolete

>From 6ac2eb6eeeee86bb5ffaa98791da2b2de73b904f Mon Sep 17 00:00:00 2001
>From: Martin Schwenke <martin@meltin.net>
>Date: Mon, 13 Aug 2018 12:18:51 +1000
>Subject: [PATCH] ctdb-common: Fix aliasing issue in IPv6 checksum
>
>Since commit 9c51b278b1700cd5f3e2addc19b7c711cc2ea10b the compiler has
>been able to inline the affected call to uint16_checksum().  Given
>that the data (phdr) is being accessed by an incompatible
>pointer (data) there is an aliasing problem when the call is inlined.
>This results in incorrect behaviour with -O2/-O3 when compiling with
>at least GCC 6, 7, and 8.
>
>Fix this by making the types compatible.
>
>Also fixes CID 1437604 (Reliance on integer endianness).  This is a
>false positive because the uint16_checksum doesn't depend on the order
>of the input uint16_t items.
>
>https://bugzilla.samba.org/show_bug.cgi?id=13588
>
>Pair-programmed-with: Amitay Isaacs <amitay@gmail.com>
>Signed-off-by: Martin Schwenke <martin@meltin.net>
>Reviewed-by: Amitay Isaacs <amitay@gmail.com>
>(cherry picked from commit 48335725deecdbdb24a9176cf31e9611c9deda49)
>---
> ctdb/common/system_socket.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
>diff --git a/ctdb/common/system_socket.c b/ctdb/common/system_socket.c
>index 62cc782a224..75286795d77 100644
>--- a/ctdb/common/system_socket.c
>+++ b/ctdb/common/system_socket.c
>@@ -270,16 +270,20 @@ static uint16_t ip_checksum(uint16_t *data, size_t n, struct ip *ip)
> 
> static uint16_t ip6_checksum(uint16_t *data, size_t n, struct ip6_hdr *ip6)
> {
>-	uint32_t phdr[2];
>+	uint16_t phdr[3];
> 	uint32_t sum = 0;
> 	uint16_t sum2;
>+	uint32_t len;
> 
> 	sum += uint16_checksum((uint16_t *)(void *)&ip6->ip6_src, 16);
> 	sum += uint16_checksum((uint16_t *)(void *)&ip6->ip6_dst, 16);
> 
>-	phdr[0] = htonl(n);
>-	phdr[1] = htonl(ip6->ip6_nxt);
>-	sum += uint16_checksum((uint16_t *)phdr, 8);
>+	len = htonl(n);
>+	phdr[0] = len & UINT16_MAX;
>+	phdr[1] = (len >> 16) & UINT16_MAX;
>+	/* ip6_nxt is only 8 bits, so fits comfortably into a uint16_t */
>+	phdr[2] = htons(ip6->ip6_nxt);
>+	sum += uint16_checksum(phdr, sizeof(phdr));
> 
> 	sum += uint16_checksum(data, n);
> 
>-- 
>2.18.0
>

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amitay: review+

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