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From:   Gaurav Singh <gaurav1086@gmail.com>
To:     gaurav1086@gmail.com, Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Jesper Dangaard Brouer <hawk@kernel.org>,
        John Fastabend <john.fastabend@gmail.com>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        Andrii Nakryiko <andriin@fb.com>,
        KP Singh <kpsingh@chromium.org>,
        netdev@vger.kernel.org (open list:XDP (eXpress Data Path)),
        bpf@vger.kernel.org (open list:XDP (eXpress Data Path)),
        linux-kernel@vger.kernel.org (open list)
Subject: [PATCH] xdp_rxq_info_user: Add null check after malloc
Date:   Tue,  9 Jun 2020 23:01:36 -0400
Message-Id: <20200610030145.17263-1-gaurav1086@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Signed-off-by: Gaurav Singh <gaurav1086@gmail.com>

The memset call is made right after malloc call which
can return a NULL pointer upon failure causing a 
segmentation fault. Fix this by adding a null check 
right after malloc() and then do memset().

---
 samples/bpf/xdp_rxq_info_user.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/samples/bpf/xdp_rxq_info_user.c b/samples/bpf/xdp_rxq_info_user.c
index 4fe47502ebed..2d03c84a4cca 100644
--- a/samples/bpf/xdp_rxq_info_user.c
+++ b/samples/bpf/xdp_rxq_info_user.c
@@ -202,11 +202,11 @@ static struct datarec *alloc_record_per_cpu(void)
 
 	size = sizeof(struct datarec) * nr_cpus;
 	array = malloc(size);
-	memset(array, 0, size);
 	if (!array) {
 		fprintf(stderr, "Mem alloc error (nr_cpus:%u)\n", nr_cpus);
 		exit(EXIT_FAIL_MEM);
 	}
+	memset(array, 0, size);
 	return array;
 }
 
@@ -218,11 +218,11 @@ static struct record *alloc_record_per_rxq(void)
 
 	size = sizeof(struct record) * nr_rxqs;
 	array = malloc(size);
-	memset(array, 0, size);
 	if (!array) {
 		fprintf(stderr, "Mem alloc error (nr_rxqs:%u)\n", nr_rxqs);
 		exit(EXIT_FAIL_MEM);
 	}
+	memset(array, 0, size);
 	return array;
 }
 
@@ -233,11 +233,11 @@ static struct stats_record *alloc_stats_record(void)
 	int i;
 
 	rec = malloc(sizeof(*rec));
-	memset(rec, 0, sizeof(*rec));
 	if (!rec) {
 		fprintf(stderr, "Mem alloc error\n");
 		exit(EXIT_FAIL_MEM);
 	}
+	memset(rec, 0, sizeof(*rec));
 	rec->rxq = alloc_record_per_rxq();
 	for (i = 0; i < nr_rxqs; i++)
 		rec->rxq[i].cpu = alloc_record_per_cpu();
-- 
2.17.1