[alsa-devel] [PATCH] pcm: fix buffer overflow in snd_pcm_chmap_print()

[Anssi Hannula]

The size argument is wrong for one of the snprintf() calls in
snd_pcm_chmap_print(), allowing an overflow to happen (the user-provided
buffer may be written data up to 2x its actual size).

Seen in an user report here: http://trac.kodi.tv/ticket/15641

Signed-off-by: Anssi Hannula <anssi.hannula at iki.fi>
---
 src/pcm/pcm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/pcm/pcm.c b/src/pcm/pcm.c
index baa47c7..e74e02f 100644
--- a/src/pcm/pcm.c
+++ b/src/pcm/pcm.c
@@ -7621,7 +7621,7 @@ int snd_pcm_chmap_print(const snd_pcm_chmap_t *map, size_t maxlen, char *buf)
 				return -ENOMEM;
 		}
 		if (map->pos[i] & SND_CHMAP_DRIVER_SPEC)
-			len += snprintf(buf + len, maxlen, "%d", p);
+			len += snprintf(buf + len, maxlen - len, "%d", p);
 		else {
 			const char *name = chmap_names[p];
 			if (name)
-- 
1.8.4.5