Re: [PATCH] drm/xe/rtp: Fix out-of-bounds array access

[Nirmoy Das <nirmoy.das@linux.intel.com>]

On 6/28/2024 6:17 PM, Lucas De Marchi wrote:
> Increment the counter before checking for number of rules, otherwise
> when there's no XE_RTP_MATCH_OR an out-of-bounds access is done, as
> reported by kasan:
>
> 	BUG: KASAN: global-out-of-bounds in rule_matches+0xb6d/0x11c0 [xe]
> 	Read of size 1 at addr ffffffffa0a50b70 by task systemd-udevd/243
>
> Fixes: dc72c52a42e0 ("drm/xe/rtp: Allow to OR rules")
> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
> Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>


> ---
>   drivers/gpu/drm/xe/xe_rtp.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/xe/xe_rtp.c b/drivers/gpu/drm/xe/xe_rtp.c
> index 5b27f7c45ea3..02e28274282f 100644
> --- a/drivers/gpu/drm/xe/xe_rtp.c
> +++ b/drivers/gpu/drm/xe/xe_rtp.c
> @@ -121,7 +121,7 @@ static bool rule_matches(const struct xe_device *xe,
>   			 * Advance rules until we find XE_RTP_MATCH_OR to check
>   			 * if there's another set of conditions to check
>   			 */
> -			while (i < n_rules && rules[++i].match_type != XE_RTP_MATCH_OR)
> +			while (++i < n_rules && rules[i].match_type != XE_RTP_MATCH_OR)
>   				;
>   
>   			if (i >= n_rules)