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Date: Sun, 21 Dec 2008 14:42:18 +0100 From: Vegard Nossum <vegard.nossum@...il.com> To: "David S. Miller" <davem@...emloft.net> Cc: Thomas Graf <tgraf@...g.ch>, Eugene Teo <eugeneteo@...nel.sg>, Andrew Morton <akpm@...ux-foundation.org>, Al Viro <viro@...iv.linux.org.uk>, netdev@...r.kernel.org, linux-kernel@...r.kernel.org Subject: [PATCH] netlink: fix (theoretical) overrun in message iteration >From bb805d89e84ddb11c9bb58afcfd9a6b37bbe5a9b Mon Sep 17 00:00:00 2001 From: Vegard Nossum <vegard.nossum@...il.com> Date: Sun, 21 Dec 2008 14:20:49 +0100 Subject: [PATCH] netlink: fix (theoretical) overrun in message iteration See commit 1045b03e07d85f3545118510a587035536030c1c for a detailed explanation of why this patch is necessary. In short, nlmsg_next() can make "remaining" go negative, and the remaining >= sizeof(...) comparison will promote "remaining" to an unsigned type, which means that the expression will evaluate to true for negative numbers, even though it was not intended. I put "theoretical" in the title because I have no evidence that this can actually happen, but I suspect that a crafted netlink packet can trigger some badness. Note that the last test, which seemingly has the exact same problem (also true for nla_ok()), is perfectly OK, since we already know that remaining is positive. Cc: Thomas Graf <tgraf@...g.ch> Signed-off-by: Vegard Nossum <vegard.nossum@...il.com> --- include/net/netlink.h | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/include/net/netlink.h b/include/net/netlink.h index 3643bbb..13dd525 100644 --- a/include/net/netlink.h +++ b/include/net/netlink.h @@ -332,7 +332,7 @@ static inline int nlmsg_attrlen(const struct nlmsghdr *nlh, int hdrlen) */ static inline int nlmsg_ok(const struct nlmsghdr *nlh, int remaining) { - return (remaining >= sizeof(struct nlmsghdr) && + return (remaining >= (int) sizeof(struct nlmsghdr) && nlh->nlmsg_len >= sizeof(struct nlmsghdr) && nlh->nlmsg_len <= remaining); } -- 1.5.6.5 -- 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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