From 6649b5eda13142b1d7b416bb4b1c66c50657433a Mon Sep 17 00:00:00 2001 From: Muhammad Usama Anjum Date: Fri, 9 Apr 2021 03:01:29 +0500 Subject: [PATCH] net: ipv6: check for validity before dereferencing cfg->fc_nlinfo.nlh commit 864db232dc7036aa2de19749c3d5be0143b24f8f upstream. nlh is being checked for validtity two times when it is dereferenced in this function. Check for validity again when updating the flags through nlh pointer to make the dereferencing safe. CC: Addresses-Coverity: ("NULL pointer dereference") Signed-off-by: Muhammad Usama Anjum Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv6/route.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 46df6345bb99..3a9bd9687e7d 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -5183,9 +5183,11 @@ static int ip6_route_multipath_add(struct fib6_config *cfg, * nexthops have been replaced by first new, the rest should * be added to it. */ - cfg->fc_nlinfo.nlh->nlmsg_flags &= ~(NLM_F_EXCL | - NLM_F_REPLACE); - cfg->fc_nlinfo.nlh->nlmsg_flags |= NLM_F_CREATE; + if (cfg->fc_nlinfo.nlh) { + cfg->fc_nlinfo.nlh->nlmsg_flags &= ~(NLM_F_EXCL | + NLM_F_REPLACE); + cfg->fc_nlinfo.nlh->nlmsg_flags |= NLM_F_CREATE; + } nhn++; }