[PATCH 3.4-stable][CVE] HID: picolcd_core: validate output report details

[Kefeng Wang <wangkefeng.wang@huawei.com>]

From: Kees Cook <keescook@chromium.org>

Hi Kees, Jiri or Greg,

This patch has been backported to 3.2 stable tree.
It is a CVE bugfix, and looks applicable to stable-3.4.
It prevents from triggering a NULL dereference during
atrr file writing if a HID device send a malicious output
report.

NOTE:
Rename file drivers/hid/hid-picolcd_core.c
	->  drivers/hid/hid-picolcd.c.

===========

From: Kees Cook <keescook@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@suse.cz: changed

	report->maxfield < 1

to

	report->maxfield != 1

as suggested by Bruno].

CVE-2013-2899

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: stable@kernel.org
Reviewed-by: Bruno Prémont <bonbons@linux-vserver.org>
Acked-by: Bruno Prémont <bonbons@linux-vserver.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
[Kefeng: backported to stable 3.4: adjust filename]
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 drivers/hid/hid-picolcd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hid/hid-picolcd.c b/drivers/hid/hid-picolcd.c
index 45c3433..95f9047 100644
--- a/drivers/hid/hid-picolcd.c
+++ b/drivers/hid/hid-picolcd.c
@@ -1424,7 +1424,7 @@ 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'))
-- 
1.8.2.2