From 619e803d3c1b7bcc17c45e81f309d0b9b3df2d5d Mon Sep 17 00:00:00 2001 From: Vegard Nossum Date: Thu, 25 Dec 2008 17:21:17 -0800 Subject: netlink: fix (theoretical) overrun in message iteration See commit 1045b03e07d85f3545118510a587035536030c1c ("netlink: fix overrun in attribute iteration") 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. Signed-off-by: Vegard Nossum Signed-off-by: David S. Miller --- include/net/netlink.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/net/netlink.h b/include/net/netlink.h index 46b7764f1774..8a6150a3f4c7 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); } -- cgit v1.2.2