[PATCH 1/1] HID: core: Fix OOB read in hid_get_report for numbered reports

[Lee Jones]

When a caller passes a size of 0 to hid_report_raw_event() for a
numbered report, the function originally called hid_get_report() before
performing any size validation.

Inside hid_get_report(), if the report is numbered (report_enum->numbered
is true), it unconditionally dereferences data[0] to extract the report ID.
With a size of 0, this results in an out-of-bounds read or kernel panic.

Fix this by moving the numbered report size validation check before the
call to hid_get_report(), ensuring that size is at least 1 before
dereferencing the data pointer.

Fixes: 2c85c61d1332 ("HID: pass the buffer size to hid_report_raw_event")
Signed-off-by: Lee Jones <lee@xxxxxxxxxx>
---
 drivers/hid/hid-core.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 41a79e43c82b..cf123347a2af 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -2045,6 +2045,13 @@ int hid_report_raw_event(struct hid_device *hid, enum hid_report_type type, u8 *
 	u8 *cdata = data;
 	int ret = 0;
 
+	if (report_enum->numbered && (size < 1 || bufsize < 1)) {
+		hid_warn_ratelimited(hid,
+				     "Event data for numbered report is too short (%d vs %zu)\n",
+				     size, bufsize);
+		return -EINVAL;
+	}
+
 	report = hid_get_report(report_enum, data);
 	if (!report)
 		return 0;
-- 
2.54.0.1136.gdb2ca164c4-goog