[PATCH 5.15.y] HID: core: Mitigate potential OOB by removing bogus memset()

[PATCH 5.15.y] HID: core: Mitigate potential OOB by removing bogus memset()

[Wenshan Lan]

From: Lee Jones <lee@kernel.org>

[ Upstream commit 0a3fe972a7cb1404f693d6f1711f32bc1d244b1c ]

The memset() in hid_report_raw_event() has the good intention of
clearing out bogus data by zeroing the area from the end of the incoming
data string to the assumed end of the buffer.  However, as we have
previously seen, doing so can easily result in OOB reads and writes in
the subsequent thread of execution.

The current suggestion from one of the HID maintainers is to remove the
memset() and simply return if the incoming event buffer size is not
large enough to fill the associated report.

Suggested-by Benjamin Tissoires <bentiss@kernel.org>

Signed-off-by: Lee Jones <lee@kernel.org>
[bentiss: changed the return value]
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
[ Replace hid_warn_ratelimited() with hid_warn() in v5.15. ]
Signed-off-by: Wenshan Lan <jetlan9@163.com>
---
 drivers/hid/hid-core.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 4fb573ee31b2..2c2714fa988e 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -1807,9 +1807,10 @@ int hid_report_raw_event(struct hid_device *hid, int type, u8 *data, u32 size,
 		rsize = max_buffer_size;
 
 	if (csize < rsize) {
-		dbg_hid("report %d is too short, (%d < %d)\n", report->id,
-				csize, rsize);
-		memset(cdata + csize, 0, rsize - csize);
+		hid_warn(hid, "Event data for report %d was too short (%d vs %d)\n",
+			 report->id, rsize, csize);
+		ret = -EINVAL;
+		goto out;
 	}
 
 	if ((hid->claimed & HID_CLAIMED_HIDDEV) && hid->hiddev_report_event)
-- 
2.43.0