[PATCH 74/93] HID: picolcd_core: validate output report details

[Kamal Mostafa]

3.8.13.10 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Kees Cook <keescook at chromium.org>

commit 1e87a2456b0227ca4ab881e19a11bb99d164e792 upstream.

A HID device could send a malicious output report that would cause the
picolcd HID driver to trigger a NULL dereference during attr file writing.

[jkosina at suse.cz: changed

	report->maxfield < 1

to

	report->maxfield != 1

as suggested by Bruno].

CVE-2013-2899

Signed-off-by: Kees Cook <keescook at chromium.org>
Reviewed-by: Bruno Prémont <bonbons at linux-vserver.org>
Acked-by: Bruno Prémont <bonbons at linux-vserver.org>
Signed-off-by: Jiri Kosina <jkosina at suse.cz>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/hid/hid-picolcd_core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hid/hid-picolcd_core.c b/drivers/hid/hid-picolcd_core.c
index 86df26e..775252d 100644
--- a/drivers/hid/hid-picolcd_core.c
+++ b/drivers/hid/hid-picolcd_core.c
@@ -292,7 +292,7 @@ static ssize_t picolcd_operation_mode_store(struct device *dev,
 		buf += 10;
 		cnt -= 10;
 	}
-	if (!report)
+	if (!report || report->maxfield != 1)
 		return -EINVAL;
 
 	while (cnt > 0 && (buf[cnt-1] == '\n' || buf[cnt-1] == '\r'))
-- 
1.8.1.2