[PATCH 3.10 146/173] media: av7110_hw: Dont use dynamic static allocation

Greg Kroah-Hartman
2013-12-02T19:12:09Z

From: Mauro Carvalho Chehab <m.chehab@samsung.com>

commit 5bf30b3bc4ff80ef71a733a1f459cca4fa507892 upstream.

Dynamic static allocation is evil, as Kernel stack is too low, and
compilation complains about it on some archs:
drivers/media/pci/ttpci/av7110_hw.c:510:1: warning: 'av7110_fw_cmd' uses dynamic stack allocation [enabled by default]
Instead, let's enforce a limit for the buffer.
In the specific case of this driver, the maximum fw command size
is 6 + 2, as checked using:
$ git grep -A1 av7110_fw_cmd drivers/media/pci/ttpci/
So, use 8 for the buffer size.

Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
Reviewed-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/media/pci/ttpci/av7110_hw.c | 19 +++++++++++++++++--
1 file changed, 17 insertions(+), 2 deletions(-)

--- a/drivers/media/pci/ttpci/av7110_hw.c
+++ b/drivers/media/pci/ttpci/av7110_hw.c
@@ -22,7 +22,7 @@
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
* Or, point your browser to http://www.gnu.org/copyleft/gpl.html
*
- * the project's page is at http://www.linuxtv.org/
+ * the project's page is at http://www.linuxtv.org/
*/

/* for debugging ARM communication: */
@@ -40,6 +40,14 @@

#define _NOHANDSHAKE

+/*
+ * Max transfer size done by av7110_fw_cmd()
+ *
+ * The maximum size passed to this function is 6 bytes. The buffer also
+ * uses two additional ones for type and size. So, 8 bytes is enough.
+ */
+#define MAX_XFER_SIZE 8
+
/****************************************************************************
* DEBI functions
****************************************************************************/
@@ -488,11 +496,18 @@ static int av7110_send_fw_cmd(struct av7
int av7110_fw_cmd(struct av7110 *av7110, int type, int com, int num, ...)
{
va_list args;
- u16 buf[num + 2];
+ u16 buf[MAX_XFER_SIZE];
int i, ret;

// dprintk(4, "%p\n", av7110);

+ if (2 + num > sizeof(buf)) {
+ printk(KERN_WARNING
+ "%s: %s len=%d is too big!\n",
+ KBUILD_MODNAME, __func__, num);
+ return -EINVAL;
+ }
+
buf[0] = ((type << 8) | com);
buf[1] = num;