[PATCH 1/2] compositor-drm: Ensure strings from EDID blobs are null terminated

[Derek Foreman]

On 28/08/15 03:04 PM, Bryce Harrington wrote:
> strncpy only adds null terminating bytes if the source string is smaller
> than the destination string.  Since this function relies on the string
> being null terminated when checking its contents, we better make sure
> there is at least a \0 as the last character.
> 
> Signed-off-by: Bryce Harrington <bryce at osg.samsung.com>

Already talked about this on irc... if you look reaaaaally hard you can
prove that this is ok because the only places that currently call
edid_parse_string() use it on 13 byte long arrays that are cleared to 0
on allocation.

I think that's way too much investigation to make sure the calls are
correct, so I like this change.

Reviewed-by: Derek Foreman <derekf at osg.samsung.com>



> ---
>  src/compositor-drm.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/src/compositor-drm.c b/src/compositor-drm.c
> index f5f125a..70a3729 100644
> --- a/src/compositor-drm.c
> +++ b/src/compositor-drm.c
> @@ -1933,6 +1933,9 @@ edid_parse_string(const uint8_t *data, char text[])
>  	 * terminated or not junk. */
>  	strncpy(text, (const char *) data, 12);
>  
> +	/* guarantee our new string is null-terminated */
> +	text[12] = '\0';
> +
>  	/* remove insane chars */
>  	for (i = 0; text[i] != '\0'; i++) {
>  		if (text[i] == '\n' ||
>