[PATCH] ALSA: hda - Fix and neaten print_nid_path/debug_badness

[PATCH] ALSA: hda - Fix and neaten print_nid_path/debug_badness

[Joe Perches]

print_nid_path has a possible buffer overflow if
struct nid_path.path values are > 256.

Avoid this and neaten the output to remove the leading ':'

Neaten debug_badness to always verify arguments.

Signed-off-by: Joe Perches <joe@perches.com>
---
 sound/pci/hda/hda_generic.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/sound/pci/hda/hda_generic.c b/sound/pci/hda/hda_generic.c
index 589e47c..b293583 100644
--- a/sound/pci/hda/hda_generic.c
+++ b/sound/pci/hda/hda_generic.c
@@ -350,16 +350,16 @@ static void print_nid_path(struct hda_codec *codec,
 			   const char *pfx, struct nid_path *path)
 {
 	char buf[40];
+	char *pos = buf;
 	int i;
 
+	*pos = 0;
+	for (i = 0; i < path->depth; i++)
+		pos += scnprintf(pos, sizeof(buf) - (pos - buf), "%s%02x",
+				 pos != buf ? ":" : "",
+				 path->path[i]);
 
-	buf[0] = 0;
-	for (i = 0; i < path->depth; i++) {
-		char tmp[4];
-		sprintf(tmp, ":%02x", path->path[i]);
-		strlcat(buf, tmp, sizeof(buf));
-	}
-	codec_dbg(codec, "%s path: depth=%d %s\n", pfx, path->depth, buf);
+	codec_dbg(codec, "%s path: depth=%d '%s'\n", pfx, path->depth, buf);
 }
 
 /* called recursively */
@@ -1700,9 +1700,11 @@ static int fill_and_eval_dacs(struct hda_codec *codec,
 #define DEBUG_BADNESS
 
 #ifdef DEBUG_BADNESS
-#define debug_badness(fmt, args...)	codec_dbg(codec, fmt, ##args)
+#define debug_badness(fmt, ...)						\
+	codec_dbg(codec, fmt, ##__VA_ARGS__)
 #else
-#define debug_badness(...)
+#define debug_badness(fmt, ...)						\
+	do { if (0) codec_dbg(codec, fmt, ##__VA_ARGS__); } while (0)
 #endif
 
 #ifdef DEBUG_BADNESS

Re: [PATCH] ALSA: hda - Fix and neaten print_nid_path/debug_badness

[Takashi Iwai]

At Sat, 05 Jul 2014 13:02:02 -0700,
Joe Perches wrote:
> 
> print_nid_path has a possible buffer overflow if
> struct nid_path.path values are > 256.
> 
> Avoid this and neaten the output to remove the leading ':'
> 
> Neaten debug_badness to always verify arguments.
> 
> Signed-off-by: Joe Perches <joe@perches.com>

Thanks, applied.

Although the overflow would never happen in practice (the id can't be
over 8 bit from the definition in the HD-audio controller side), it's
still better to have a proper check.


Takashi

> ---
>  sound/pci/hda/hda_generic.c | 20 +++++++++++---------
>  1 file changed, 11 insertions(+), 9 deletions(-)
> 
> diff --git a/sound/pci/hda/hda_generic.c b/sound/pci/hda/hda_generic.c
> index 589e47c..b293583 100644
> --- a/sound/pci/hda/hda_generic.c
> +++ b/sound/pci/hda/hda_generic.c
> @@ -350,16 +350,16 @@ static void print_nid_path(struct hda_codec *codec,
>  			   const char *pfx, struct nid_path *path)
>  {
>  	char buf[40];
> +	char *pos = buf;
>  	int i;
>  
> +	*pos = 0;
> +	for (i = 0; i < path->depth; i++)
> +		pos += scnprintf(pos, sizeof(buf) - (pos - buf), "%s%02x",
> +				 pos != buf ? ":" : "",
> +				 path->path[i]);
>  
> -	buf[0] = 0;
> -	for (i = 0; i < path->depth; i++) {
> -		char tmp[4];
> -		sprintf(tmp, ":%02x", path->path[i]);
> -		strlcat(buf, tmp, sizeof(buf));
> -	}
> -	codec_dbg(codec, "%s path: depth=%d %s\n", pfx, path->depth, buf);
> +	codec_dbg(codec, "%s path: depth=%d '%s'\n", pfx, path->depth, buf);
>  }
>  
>  /* called recursively */
> @@ -1700,9 +1700,11 @@ static int fill_and_eval_dacs(struct hda_codec *codec,
>  #define DEBUG_BADNESS
>  
>  #ifdef DEBUG_BADNESS
> -#define debug_badness(fmt, args...)	codec_dbg(codec, fmt, ##args)
> +#define debug_badness(fmt, ...)						\
> +	codec_dbg(codec, fmt, ##__VA_ARGS__)
>  #else
> -#define debug_badness(...)
> +#define debug_badness(fmt, ...)						\
> +	do { if (0) codec_dbg(codec, fmt, ##__VA_ARGS__); } while (0)
>  #endif
>  
>  #ifdef DEBUG_BADNESS
> 
>