Re: [RFC] perf: Prevent potential null dereference

[Frederic Weisbecker <fweisbec@gmail.com>]

On Fri, Dec 03, 2010 at 01:26:05AM +0300, Cyrill Gorcunov wrote:
> In case if there is no memory we might hit null
> dereference on accessing calloc'ed data.
> 
> Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
> CC: Arnaldo Carvalho de Melo <acme@redhat.com>
> CC: Peter Zijlstra <peterz@infradead.org>
> CC: Ingo Molnar <mingo@elte.hu>
> CC: Frederic Weisbecker <fweisbec@gmail.com>
> ---
> 
> It seems exit right here is more convenient than passing error
> handling level up (which would have to exit anyway), thought
> if handling it "upper" is preferred -- just say a word.
> 
>  tools/perf/builtin-record.c |    4 ++++
>  1 file changed, 4 insertions(+)
> 
> Index: linux-2.6.git/tools/perf/builtin-record.c
> =====================================================================
> --- linux-2.6.git.orig/tools/perf/builtin-record.c
> +++ linux-2.6.git/tools/perf/builtin-record.c
> @@ -524,6 +524,10 @@ static void comm__construct(int argc, co
>  		return;
>  
>  	comm = calloc(1, size);
> +	if (!comm) {
> +		pr_err("Not enough memory to construct internal command line.\n");
> +		exit(-1);
> +	}
>  
>  	tmp = comm;
>  	for (i = 0; i < argc; i++) {


Good.

As a nit, not that it matters that much because we are very close to the starting code
anyway, but it would be better to propagate the error to the callers.

Thanks.