HID: picolcd_core: validate output report details

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>
Reviewed-by: Bruno Prémont <bonbons@linux-vserver.org>
Acked-by: Bruno Prémont <bonbons@linux-vserver.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
[bwh: Backported to 3.2: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/hid/hid-picolcd.c b/drivers/hid/hid-picolcd.c
index 01e7d2cd7c26a55170d2f7eda4e0a83cb37cb55d..1daeacabc83257f21ce0fbd37996787edaa39dab 100644 (file)
--- 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'))