[1/9] drm/i915/sdvo: Reduce the size of the on stack buffers
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Message ID 20200108181242.13650-1-ville.syrjala@linux.intel.com
State New
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Series
  • [1/9] drm/i915/sdvo: Reduce the size of the on stack buffers
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Commit Message

Ville Syrjälä Jan. 8, 2020, 6:12 p.m. UTC
From: Ville Syrjälä <ville.syrjala@linux.intel.com>

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@linux.intel.com>
---
 drivers/gpu/drm/i915/display/intel_sdvo.c | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

Comments

Jani Nikula Jan. 14, 2020, 2:52 p.m. UTC | #1
On Wed, 08 Jan 2020, Ville Syrjala <ville.syrjala@linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> 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@linux.intel.com>

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

> ---
>  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;

Patch
diff mbox series

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;