Re: [HPDD-discuss] [PATCH] staging: lustre: include: lustre_update.h: Fix for possible null pointer dereference

[Frank Zago <fzago@cray.com>]

On 01/29/2015 12:47 PM, Rickard Strandqvist wrote:
> Fix a possible null pointer dereference, there is
> otherwise a risk of a possible null pointer dereference.
>
> This was found using a static code analysis program called cppcheck
>
> Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
> ---
>   drivers/staging/lustre/lustre/include/lustre_update.h |    4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/staging/lustre/lustre/include/lustre_update.h b/drivers/staging/lustre/lustre/include/lustre_update.h
> index 84defce..00e1361 100644
> --- a/drivers/staging/lustre/lustre/include/lustre_update.h
> +++ b/drivers/staging/lustre/lustre/include/lustre_update.h
> @@ -165,12 +165,14 @@ static inline int update_get_reply_buf(struct update_reply *reply, void **buf,
>   	int  result;
>
>   	ptr = update_get_buf_internal(reply, index, &size);
> +
> +	LASSERT((ptr != NULL && size >= sizeof(int)));

Now size is tested before result. So it could assert if result < 0, 
while the function would have returned before.

> +
>   	result = *(int *)ptr;
>
>   	if (result < 0)
>   		return result;
>
> -	LASSERT((ptr != NULL && size >= sizeof(int)));
>   	*buf = ptr + sizeof(int);
>   	return size - sizeof(int);
>   }
>