netdev - Re: [PATCH] [bpf] xdp_redirect_cpu_user: Fix null pointer dereference

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Message-ID: <f803b1ad-cccd-750f-01e4-e1769ab1d538@iogearbox.net>
Date:   Tue, 16 Jun 2020 15:10:14 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Gaurav Singh <gaurav1086@...il.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        "open list:BPF (Safe dynamic programs and tools)" 
        <netdev@...r.kernel.org>,
        "open list:BPF (Safe dynamic programs and tools)" 
        <bpf@...r.kernel.org>, open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] [bpf] xdp_redirect_cpu_user: Fix null pointer dereference

On 6/14/20 9:04 PM, 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@...il.com>

Squashed all three same fixes into one and pushed to bpf, thanks!

> @@ -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));

For the record, this one is buggy, so I fixed it up as well.

>   	if (!rec) {
>   		fprintf(stderr, "Mem alloc error\n");
>   		exit(EXIT_FAIL_MEM);
> 

Thanks,
Daniel