linux-kernel - [PATCH] hda_hwdep: Fix possible buffer overflow

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Message-Id: <1319615292-27396-1-git-send-email-alexander.stein@systec-electronic.com>
Date:	Wed, 26 Oct 2011 09:48:12 +0200
From:	Alexander Stein <alexander.stein@...tec-electronic.com>
To:	Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.de>
Cc:	alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
	Alexander Stein <alexander.stein@...tec-electronic.com>
Subject: [PATCH] hda_hwdep: Fix possible buffer overflow

If a line in the firmware file is larger than the given buffer size (and
so the firmware file size), size is set to a value larger than the actual
buffer size. This results in an overflow in the buffer passed.
Fix this by copying only up to 127 chars per line.

Signed-off-by: Alexander Stein <alexander.stein@...tec-electronic.com>
---
 sound/pci/hda/hda_hwdep.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/sound/pci/hda/hda_hwdep.c b/sound/pci/hda/hda_hwdep.c
index bf3ced5..61da08d 100644
--- a/sound/pci/hda/hda_hwdep.c
+++ b/sound/pci/hda/hda_hwdep.c
@@ -745,6 +745,7 @@ static int parse_line_mode(char *buf, struct hda_bus *bus)
  * if successfully copied a line
  *
  * the spaces at the beginning and the end of the line are stripped
+ * lines read are clamped to 127 chars
  */
 static int get_line_from_fw(char *buf, int size, struct firmware *fw)
 {
@@ -756,8 +757,6 @@ static int get_line_from_fw(char *buf, int size, struct firmware *fw)
 	}
 	if (!fw->size)
 		return 0;
-	if (size < fw->size)
-		size = fw->size;
 
 	for (len = 0; len < fw->size; len++) {
 		if (!*p)
@@ -768,7 +767,8 @@ static int get_line_from_fw(char *buf, int size, struct firmware *fw)
 			break;
 		}
 		if (len < size)
-			*buf++ = *p++;
+			*buf++ = *p;
+		p++;
 	}
 	*buf = 0;
 	fw->size -= len;
-- 
1.7.3.4

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