[lxc-devel] [PATCH] namespace: check stack allocation for clone succeeds

[Nathan Lynch]

On Mon, 2011-04-11 at 12:42 -0400, Michael Santos wrote:
> ---
>  src/lxc/namespace.c |    7 ++++++-
>  1 files changed, 6 insertions(+), 1 deletions(-)
> 
> diff --git a/src/lxc/namespace.c b/src/lxc/namespace.c
> index 8263fe7..5928eaa 100644
> --- a/src/lxc/namespace.c
> +++ b/src/lxc/namespace.c
> @@ -67,9 +67,14 @@ pid_t lxc_clone(int (*fn)(void *), void *arg, int flags)
>  	};
>  
>  	long stack_size = sysconf(_SC_PAGESIZE);
> - 	void *stack = alloca(stack_size) + stack_size;
> +	void *stack = alloca(stack_size);
>  	pid_t ret;
>  
> +	if (stack == NULL)
> +		ERROR("failed to allocate memory");
> +
> +	stack += stack_size;
> +

Please see the man page, in particular "Notes on the GNU Version" and
"BUGS", for why this patch doesn't really make sense.

http://www.kernel.org/doc/man-pages/online/pages/man3/alloca.3.html