From ff5eb74b7be8cfe152c571d5de3f4bbb81c10c7a 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 03d1a61b4729..70c37951b3f6 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -3069,9 +3069,11 @@ static int ip6_route_multipath_add(struct fib6_config *cfg) * nexthops have been replaced by first new, the rest should * be added to it.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++; }