[apparmor] [patch 06/12] parser: fix /proc version file read

[Seth Arnold]

On Tue, Dec 03, 2013 at 12:12:22PM -0800, Steve Beattie wrote:
> The parser was not checking for an error when reading from
> /proc/sys/kernel/osrelease. Additionally, valgrind was complaining
> because of the uninitialized space in the buffer in between where
> the read(2) had deposited its data and where the parser was writing
> a trailing NUL to close the string. This patch fixes the above by
> writing the NUL byte at the position at the end of the read characters
> and checks for a negative result from the read() call.
> 
> Signed-off-by: Steve Beattie <steve at nxnw.org>

Wow that valgrind really is picky. :)

Acked-by: Seth Arnold <seth.arnold at canonical.com>

> ---
>  parser/parser_misc.c |    6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> Index: b/parser/parser_misc.c
> ===================================================================
> --- a/parser/parser_misc.c
> +++ b/parser/parser_misc.c
> @@ -311,11 +311,11 @@ static size_t kernel_af_max(void) {
>  	if (!fd)
>  		/* fall back to default provided during build */
>  		return 0;
> -	res = read(fd, &buffer, sizeof(buffer));
> +	res = read(fd, &buffer, sizeof(buffer) - 1);
>  	close(fd);
> -	if (!res)
> +	if (res <= 0)
>  		return 0;
> -	buffer[sizeof(buffer)-1] = '\0';
> +	buffer[res] = '\0';
>  	res = sscanf(buffer, "2.6.%d", &major);
>  	if (res != 1)
>  		return 0;
> 
> 
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