* [PATCH] [bpf] xdp_monitor_user: Fix null pointer dereference
@ 2020-06-14 18:41 Gaurav Singh
2020-06-16 7:05 ` John Fastabend
0 siblings, 1 reply; 2+ messages in thread
From: Gaurav Singh @ 2020-06-14 18:41 UTC (permalink / raw)
To: gaurav1086, Alexei Starovoitov, Daniel Borkmann, Martin KaFai Lau,
Song Liu, Yonghong Song, Andrii Nakryiko, John Fastabend,
KP Singh, David S. Miller, Jakub Kicinski, Jesper Dangaard Brouer,
open list:BPF (Safe dynamic programs and tools),
open list:BPF (Safe dynamic programs and tools), open list
Memset() on the pointer right after malloc() can cause
a null pointer dereference if it failed to allocate memory.
Fix this by replacing malloc/memset with a single calloc().
Signed-off-by: Gaurav Singh <gaurav1086@gmail.com>
---
samples/bpf/xdp_monitor_user.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
diff --git a/samples/bpf/xdp_monitor_user.c b/samples/bpf/xdp_monitor_user.c
index dd558cbb2309..ef53b93db573 100644
--- 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);
--
2.17.1
^ permalink raw reply related [flat|nested] 2+ messages in thread* RE: [PATCH] [bpf] xdp_monitor_user: Fix null pointer dereference
2020-06-14 18:41 [PATCH] [bpf] xdp_monitor_user: Fix null pointer dereference Gaurav Singh
@ 2020-06-16 7:05 ` John Fastabend
0 siblings, 0 replies; 2+ messages in thread
From: John Fastabend @ 2020-06-16 7:05 UTC (permalink / raw)
To: Gaurav Singh, gaurav1086, Alexei Starovoitov, Daniel Borkmann,
Martin KaFai Lau, Song Liu, Yonghong Song, Andrii Nakryiko,
John Fastabend, KP Singh, David S. Miller, Jakub Kicinski,
Jesper Dangaard Brouer,
(open list:BPF \(Safe dynamic programs and tools\)),
open list:BPF (Safe dynamic programs and tools),
(open list:BPF \(Safe dynamic programs and tools\) open list)
Gaurav Singh wrote:
> Memset() on the pointer right after malloc() can cause
> a null pointer dereference if it failed to allocate memory.
> Fix this by replacing malloc/memset with a single calloc().
>
> Signed-off-by: Gaurav Singh <gaurav1086@gmail.com>
> ---
> samples/bpf/xdp_monitor_user.c | 8 ++------
> 1 file changed, 2 insertions(+), 6 deletions(-)
>
> diff --git a/samples/bpf/xdp_monitor_user.c b/samples/bpf/xdp_monitor_user.c
> index dd558cbb2309..ef53b93db573 100644
> --- 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);
> --
> 2.17.1
>
Acked-by: John Fastabend <john.fastabend@gmail.com>
^ permalink raw reply [flat|nested] 2+ messages in thread
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