Re: [edk2-platforms][PATCH 1/1] Platform/RPi: Prevent buffer over-read when the command line is empty

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 11/4/19 5:06 PM, Pete Batard wrote:
> From: Andrei Warkentin <andrey.warkentin@gmail.com>
> 
> It is possible for the command line to be empty
> (Cmd->TagHead.TagValueSize = 0), in which case the code should not
> attempt to read the value at CommandLine[-1].

Oops...

Reviewed-by: Philippe Mathieu-Daude <philmd@redhat.com>

> Signed-off-by: Pete Batard <pete@akeo.ie>
> ---
>   Platform/RaspberryPi/Drivers/RpiFirmwareDxe/RpiFirmwareDxe.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/Platform/RaspberryPi/Drivers/RpiFirmwareDxe/RpiFirmwareDxe.c b/Platform/RaspberryPi/Drivers/RpiFirmwareDxe/RpiFirmwareDxe.c
> index 5a9d4c3f1787..9b4aa068857c 100644
> --- a/Platform/RaspberryPi/Drivers/RpiFirmwareDxe/RpiFirmwareDxe.c
> +++ b/Platform/RaspberryPi/Drivers/RpiFirmwareDxe/RpiFirmwareDxe.c
> @@ -927,7 +927,8 @@ RpiFirmwareGetCommmandLine (
>   
>     CopyMem (CommandLine, Cmd->CommandLine, Cmd->TagHead.TagValueSize);
>   
> -  if (CommandLine[Cmd->TagHead.TagValueSize - 1] != '\0') {
> +  if (Cmd->TagHead.TagValueSize == 0 ||
> +      CommandLine[Cmd->TagHead.TagValueSize - 1] != '\0') {
>       //
>       // Add a NUL terminator if required.
>       //
>