From: John Fastabend <john.fastabend@gmail.com>
To: Gaurav Singh <gaurav1086@gmail.com>,
gaurav1086@gmail.com, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>, Andrii Nakryiko <andriin@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@chromium.org>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Jesper Dangaard Brouer <hawk@kernel.org>,
"(open list:BPF \\(Safe dynamic programs and tools\\))"
<netdev@vger.kernel.org>,
bpf@vger.kernel.org (open list:BPF \(Safe dynamic programs and
tools\)),
"(open list:BPF \\(Safe dynamic programs and tools\\) open
list)" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] [bpf] xdp_redirect_cpu_user: Fix null pointer dereference
Date: Tue, 16 Jun 2020 00:07:40 -0700 [thread overview]
Message-ID: <5ee86fbc41c03_4be02ab1b668a5b422@john-XPS-13-9370.notmuch> (raw)
In-Reply-To: <20200614190434.31321-1-gaurav1086@gmail.com>
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_redirect_cpu_user.c | 11 +++--------
> 1 file changed, 3 insertions(+), 8 deletions(-)
>
> diff --git a/samples/bpf/xdp_redirect_cpu_user.c b/samples/bpf/xdp_redirect_cpu_user.c
> index f3468168982e..2ae7a9a1d950 100644
> --- 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);
> @@ -222,11 +219,9 @@ static struct datarec *alloc_record_per_cpu(void)
> static struct stats_record *alloc_stats_record(void)
> {
> struct stats_record *rec;
> - int i, size;
> + int i;
>
> - size = sizeof(*rec) + n_cpus * sizeof(struct record);
> - rec = malloc(size);
> - memset(rec, 0, size);
> + rec = calloc(n_cpus + 1, sizeof(struct record));
> if (!rec) {
> fprintf(stderr, "Mem alloc error\n");
> exit(EXIT_FAIL_MEM);
> --
> 2.17.1
>
Acked-by: John Fastabend <john.fastabend@gmail.com>
next prev parent reply other threads:[~2020-06-16 7:07 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-14 19:04 [PATCH] [bpf] xdp_redirect_cpu_user: Fix null pointer dereference Gaurav Singh
2020-06-16 7:07 ` John Fastabend [this message]
2020-06-16 13:10 ` Daniel Borkmann
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