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    Subject[PATCH 5.7 119/265] bpf, xdp, samples: Fix null pointer dereference in *_user code
    Date
    From: Gaurav Singh <gaurav1086@gmail.com>

    [ Upstream commit 6903cdae9f9f08d61e49c16cbef11c293e33a615 ]

    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>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    samples/bpf/xdp_monitor_user.c | 8 ++------
    samples/bpf/xdp_redirect_cpu_user.c | 7 ++-----
    samples/bpf/xdp_rxq_info_user.c | 13 +++----------
    3 files changed, 7 insertions(+), 21 deletions(-)

    diff --git a/samples/bpf/xdp_monitor_user.c b/samples/bpf/xdp_monitor_user.c
    index dd558cbb23094..ef53b93db5732 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);
    diff --git a/samples/bpf/xdp_redirect_cpu_user.c b/samples/bpf/xdp_redirect_cpu_user.c
    index 9b8f21abeac47..e86fed5cdb92c 100644
    --- a/samples/bpf/xdp_redirect_cpu_user.c
    +++ b/samples/bpf/xdp_redirect_cpu_user.c
    @@ -210,11 +210,8 @@ 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);
    @@ -229,11 +226,11 @@ 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 4fe47502ebed4..caa4e7ffcfc7b 100644
    --- 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);
    --
    2.25.1
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