On Wed, 08 Jan 2020, Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx> wrote:
> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> The strings we want to print to the on stack buffers should
> be no more than
> 8 * 3 + strlen("(GET_SCALED_HDTV_RESOLUTION_SUPPORT)") + 1 = 61
> bytes. So let's shrink the buffers down to 64 bytes.
>
> Also switch the BUG_ON()s to WARN_ON()s if I made a mistake in
> my arithmentic.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Reviewed-by: Jani Nikula <jani.nikula@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_sdvo.c | 19 ++++++++-----------
> 1 file changed, 8 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_sdvo.c b/drivers/gpu/drm/i915/display/intel_sdvo.c
> index 8758ee2a4442..02119c827c80 100644
> --- a/drivers/gpu/drm/i915/display/intel_sdvo.c
> +++ b/drivers/gpu/drm/i915/display/intel_sdvo.c
> @@ -414,12 +414,10 @@ static void intel_sdvo_debug_write(struct intel_sdvo *intel_sdvo, u8 cmd,
> {
> const char *cmd_name;
> int i, pos = 0;
> -#define BUF_LEN 256
> - char buffer[BUF_LEN];
> + char buffer[64];
>
> #define BUF_PRINT(args...) \
> - pos += snprintf(buffer + pos, max_t(int, BUF_LEN - pos, 0), args)
> -
> + pos += snprintf(buffer + pos, max_t(int, sizeof(buffer) - pos, 0), args)
>
> for (i = 0; i < args_len; i++) {
> BUF_PRINT("%02X ", ((u8 *)args)[i]);
> @@ -433,9 +431,9 @@ static void intel_sdvo_debug_write(struct intel_sdvo *intel_sdvo, u8 cmd,
> BUF_PRINT("(%s)", cmd_name);
> else
> BUF_PRINT("(%02X)", cmd);
> - BUG_ON(pos >= BUF_LEN - 1);
> +
> + WARN_ON(pos >= sizeof(buffer) - 1);
> #undef BUF_PRINT
> -#undef BUF_LEN
>
> DRM_DEBUG_KMS("%s: W: %02X %s\n", SDVO_NAME(intel_sdvo), cmd, buffer);
> }
> @@ -540,8 +538,7 @@ static bool intel_sdvo_read_response(struct intel_sdvo *intel_sdvo,
> u8 retry = 15; /* 5 quick checks, followed by 10 long checks */
> u8 status;
> int i, pos = 0;
> -#define BUF_LEN 256
> - char buffer[BUF_LEN];
> + char buffer[64];
>
> buffer[0] = '\0';
>
> @@ -581,7 +578,7 @@ static bool intel_sdvo_read_response(struct intel_sdvo *intel_sdvo,
> }
>
> #define BUF_PRINT(args...) \
> - pos += snprintf(buffer + pos, max_t(int, BUF_LEN - pos, 0), args)
> + pos += snprintf(buffer + pos, max_t(int, sizeof(buffer) - pos, 0), args)
>
> cmd_status = sdvo_cmd_status(status);
> if (cmd_status)
> @@ -600,9 +597,9 @@ static bool intel_sdvo_read_response(struct intel_sdvo *intel_sdvo,
> goto log_fail;
> BUF_PRINT(" %02X", ((u8 *)response)[i]);
> }
> - BUG_ON(pos >= BUF_LEN - 1);
> +
> + WARN_ON(pos >= sizeof(buffer) - 1);
> #undef BUF_PRINT
> -#undef BUF_LEN
>
> DRM_DEBUG_KMS("%s: R: %s\n", SDVO_NAME(intel_sdvo), buffer);
> return true;
--
Jani Nikula, Intel Open Source Graphics Center
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