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From:   Haowen Bai <baihaowen@meizu.com>
To:     "David S. Miller" <davem@davemloft.net>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        David Ahern <dsahern@kernel.org>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>
CC:     Haowen Bai <baihaowen@meizu.com>, <netdev@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
Subject: [PATCH] net/ipv4: fix potential NULL dereference in sisfb_post_sis300()
Date:   Fri, 1 Apr 2022 11:57:12 +0800
Message-ID: <1648785432-21824-1-git-send-email-baihaowen@meizu.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

psin and psl could be null without checking null and return, so
we need to dereference after checking.

Signed-off-by: Haowen Bai <baihaowen@meizu.com>
---
 net/ipv4/igmp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index 2ad3c7b..d400080 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -2569,7 +2569,7 @@ int ip_mc_msfget(struct sock *sk, struct ip_msfilter *msf,
 	    copy_to_user(optval, msf, IP_MSFILTER_SIZE(0))) {
 		return -EFAULT;
 	}
-	if (len &&
+	if (len && psl &&
 	    copy_to_user(&optval->imsf_slist_flex[0], psl->sl_addr, len))
 		return -EFAULT;
 	return 0;
@@ -2608,7 +2608,7 @@ int ip_mc_gsfget(struct sock *sk, struct group_filter *gsf,
 	count = psl ? psl->sl_count : 0;
 	copycount = count < gsf->gf_numsrc ? count : gsf->gf_numsrc;
 	gsf->gf_numsrc = count;
-	for (i = 0; i < copycount; i++, p++) {
+	for (i = 0; i < copycount && psin && psl; i++, p++) {
 		struct sockaddr_storage ss;
 
 		psin = (struct sockaddr_in *)&ss;
-- 
2.7.4