From: Vegard Nossum Date: Fri, 26 Dec 2008 01:21:17 +0000 (-0800) Subject: netlink: fix (theoretical) overrun in message iteration X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=619e803d3c1b7bcc17c45e81f309d0b9b3df2d5d;p=GitHub%2FLineageOS%2Fandroid_kernel_samsung_universal7580.git 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 --- diff --git a/include/net/netlink.h b/include/net/netlink.h index 46b7764f177..8a6150a3f4c 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); }