bpf, xdp, samples: Fix null pointer dereference in *_user code

Memset on the pointer right after malloc can cause a NULL pointer
deference if it failed to allocate memory. A simple fix is to
replace malloc()/memset() pair with a simple call to calloc().

Fixes: 0fca931a6f21 ("samples/bpf: program demonstrating access to xdp_rxq_info")
Signed-off-by: Gaurav Singh <gaurav1086@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>

diff --git a/samples/bpf/xdp_monitor_user.c b/samples/bpf/xdp_monitor_user.c
index dd558cb..ef53b93 100644 (file)
--- a/samples/bpf/xdp_monitor_user.c
+++ b/samples/bpf/xdp_monitor_user.c
@@ -509,11 +509,8 @@ static void *alloc_rec_per_cpu(int record_size)
 {
        unsigned int nr_cpus = bpf_num_possible_cpus();
        void *array;
-       size_t size;
 
-       size = record_size * nr_cpus;
-       array = malloc(size);
-       memset(array, 0, size);
+       array = calloc(nr_cpus, record_size);
        if (!array) {
                fprintf(stderr, "Mem alloc error (nr_cpus:%u)\n", nr_cpus);
                exit(EXIT_FAIL_MEM);
@@ -528,8 +525,7 @@ static struct stats_record *alloc_stats_record(void)
        int i;
 
        /* Alloc main stats_record structure */
-       rec = malloc(sizeof(*rec));
-       memset(rec, 0, sizeof(*rec));
+       rec = calloc(1, sizeof(*rec));
        if (!rec) {
                fprintf(stderr, "Mem alloc error\n");
                exit(EXIT_FAIL_MEM);

diff --git a/samples/bpf/xdp_redirect_cpu_user.c b/samples/bpf/xdp_redirect_cpu_user.c
index f346816..f4e755e 100644 (file)
--- a/samples/bpf/xdp_redirect_cpu_user.c
+++ b/samples/bpf/xdp_redirect_cpu_user.c
@@ -207,11 +207,8 @@ static struct datarec *alloc_record_per_cpu(void)
 {
        unsigned int nr_cpus = bpf_num_possible_cpus();
        struct datarec *array;
-       size_t size;
 
-       size = sizeof(struct datarec) * nr_cpus;
-       array = malloc(size);
-       memset(array, 0, size);
+       array = calloc(nr_cpus, sizeof(struct datarec));
        if (!array) {
                fprintf(stderr, "Mem alloc error (nr_cpus:%u)\n", nr_cpus);
                exit(EXIT_FAIL_MEM);
@@ -226,11 +223,11 @@ static struct stats_record *alloc_stats_record(void)
 
        size = sizeof(*rec) + n_cpus * sizeof(struct record);
        rec = malloc(size);
-       memset(rec, 0, size);
        if (!rec) {
                fprintf(stderr, "Mem alloc error\n");
                exit(EXIT_FAIL_MEM);
        }
+       memset(rec, 0, size);
        rec->rx_cnt.cpu    = alloc_record_per_cpu();
        rec->redir_err.cpu = alloc_record_per_cpu();
        rec->kthread.cpu   = alloc_record_per_cpu();

diff --git a/samples/bpf/xdp_rxq_info_user.c b/samples/bpf/xdp_rxq_info_user.c
index 4fe4750..caa4e7f 100644 (file)
--- a/samples/bpf/xdp_rxq_info_user.c
+++ b/samples/bpf/xdp_rxq_info_user.c
@@ -198,11 +198,8 @@ static struct datarec *alloc_record_per_cpu(void)
 {
        unsigned int nr_cpus = bpf_num_possible_cpus();
        struct datarec *array;
-       size_t size;
 
-       size = sizeof(struct datarec) * nr_cpus;
-       array = malloc(size);
-       memset(array, 0, size);
+       array = calloc(nr_cpus, sizeof(struct datarec));
        if (!array) {
                fprintf(stderr, "Mem alloc error (nr_cpus:%u)\n", nr_cpus);
                exit(EXIT_FAIL_MEM);
@@ -214,11 +211,8 @@ static struct record *alloc_record_per_rxq(void)
 {
        unsigned int nr_rxqs = bpf_map__def(rx_queue_index_map)->max_entries;
        struct record *array;
-       size_t size;
 
-       size = sizeof(struct record) * nr_rxqs;
-       array = malloc(size);
-       memset(array, 0, size);
+       array = calloc(nr_rxqs, sizeof(struct record));
        if (!array) {
                fprintf(stderr, "Mem alloc error (nr_rxqs:%u)\n", nr_rxqs);
                exit(EXIT_FAIL_MEM);
@@ -232,8 +226,7 @@ static struct stats_record *alloc_stats_record(void)
        struct stats_record *rec;
        int i;
 
-       rec = malloc(sizeof(*rec));
-       memset(rec, 0, sizeof(*rec));
+       rec = calloc(1, sizeof(struct stats_record));
        if (!rec) {
                fprintf(stderr, "Mem alloc error\n");
                exit(EXIT_FAIL_MEM);