From 864db232dc7036aa2de19749c3d5be0143b24f8f 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 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 --- 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 1056b0229ffd..373d48073106 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -5209,9 +5209,11 @@ static int ip6_route_multipath_add(struct fib6_config *cfg, * nexthops have been replaced by first new, the rest should * be added to it.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++; }