Re: [PATCH] xdp_rxq_info_user: Add null check after malloc

[Daniel Borkmann]

On 6/10/20 5:01 AM, Gaurav Singh wrote:

Signed-off-by: Gaurav Singh <gaurav1...@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().

The SoB should come after the commit message here.

---
  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);

All these below are candidates for calloc(), can we just use that instead and
simplify the below.

        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();

Thanks,
Daniel