[ 21/28] HID: check for NULL field when setting values

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

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

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

From: Kees Cook <keescook@chromium.org>

commit be67b68d52fa28b9b721c47bb42068f0c1214855 upstream.

Defensively check that the field to be worked on is not NULL.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/hid/hid-core.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -993,7 +993,12 @@ EXPORT_SYMBOL_GPL(hid_output_report);
 
 int hid_set_field(struct hid_field *field, unsigned offset, __s32 value)
 {
-	unsigned size = field->report_size;
+	unsigned size;
+
+	if (!field)
+		return -1;
+
+	size = field->report_size;
 
 	hid_dump_input(field->report->device, field->usage + offset, value);