[PATCH] hda_hwdep: Fix possible buffer overflow

[PATCH] hda_hwdep: Fix possible buffer overflow

[Alexander Stein]

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@systec-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

Re: [PATCH] hda_hwdep: Fix possible buffer overflow

[Takashi Iwai]

At Wed, 26 Oct 2011 09:48:12 +0200,
Alexander Stein wrote:
> 
> 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.

Actually this check should have been

	if (size > fw->size)
		size = fw->size;

Otherwise it doesn't make sense.
If the change is OK, could you resend the patch with it?


thanks,

Takashi

> Signed-off-by: Alexander Stein <alexander.stein@systec-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
> 

Re: [PATCH] hda_hwdep: Fix possible buffer overflow

[Alexander Stein]

Hello,

On Wednesday 26 October 2011 14:58:43 Takashi Iwai wrote:
> At Wed, 26 Oct 2011 09:48:12 +0200,
> 
> Alexander Stein wrote:
> > 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.
> 
> Actually this check should have been
> 
> 	if (size > fw->size)
> 		size = fw->size;
> 
> Otherwise it doesn't make sense.
> If the change is OK, could you resend the patch with it?

IMO this check isn't even needed. This case should be catched by this check

   for (len = 0; len < fw->size; len++) {

already.
Opinions?

Alexader

> > Signed-off-by: Alexander Stein <alexander.stein@systec-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;

Re: [PATCH] hda_hwdep: Fix possible buffer overflow

[Takashi Iwai]

At Wed, 26 Oct 2011 15:15:24 +0200,
Alexander Stein wrote:
> 
> Hello,
> 
> On Wednesday 26 October 2011 14:58:43 Takashi Iwai wrote:
> > At Wed, 26 Oct 2011 09:48:12 +0200,
> > 
> > Alexander Stein wrote:
> > > 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.
> > 
> > Actually this check should have been
> > 
> > 	if (size > fw->size)
> > 		size = fw->size;
> > 
> > Otherwise it doesn't make sense.
> > If the change is OK, could you resend the patch with it?
> 
> IMO this check isn't even needed. This case should be catched by this check
> 
>    for (len = 0; len < fw->size; len++) {
> 
> already.
> Opinions?

Right, it's superfluous.  Let's get rid of it.


Takashi

[PATCH v2] hda_hwdep: Fix possible buffer overflow

[Alexander Stein]

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.

Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
---
Changes in v2:
* Just remove the erroneous check

 sound/pci/hda/hda_hwdep.c |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)

diff --git a/sound/pci/hda/hda_hwdep.c b/sound/pci/hda/hda_hwdep.c
index 72e5885..7e7d078 100644
--- a/sound/pci/hda/hda_hwdep.c
+++ b/sound/pci/hda/hda_hwdep.c
@@ -756,8 +756,6 @@ 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)
-- 
1.7.3.4

Re: [PATCH v2] hda_hwdep: Fix possible buffer overflow

[Takashi Iwai]

At Tue,  1 Nov 2011 09:40:07 +0100,
Alexander Stein wrote:
> 
> 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.
> 
> Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
> ---
> Changes in v2:
> * Just remove the erroneous check

Thanks, applied now.


Takashi

> 
>  sound/pci/hda/hda_hwdep.c |    2 --
>  1 files changed, 0 insertions(+), 2 deletions(-)
> 
> diff --git a/sound/pci/hda/hda_hwdep.c b/sound/pci/hda/hda_hwdep.c
> index 72e5885..7e7d078 100644
> --- a/sound/pci/hda/hda_hwdep.c
> +++ b/sound/pci/hda/hda_hwdep.c
> @@ -756,8 +756,6 @@ 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)
> -- 
> 1.7.3.4
>