Patch "Input: gtco - fix potential out-of-bound access" has been added to the 4.13-stable tree

This is a note to let you know that I've just added the patch titled

Input: gtco - fix potential out-of-bound access

to the 4.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
input-gtco-fix-potential-out-of-bound-access.patch
and it can be found in the queue-4.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Dmitry Torokhov <[email protected]>
Date: Mon, 23 Oct 2017 16:46:00 -0700
Subject: Input: gtco - fix potential out-of-bound access

From: Dmitry Torokhov <[email protected]>

commit a50829479f58416a013a4ccca791336af3c584c7 upstream.

parse_hid_report_descriptor() has a while (i < length) loop, which only guarantees that there's at least 1 byte in the buffer, but the loop body can read multiple bytes which causes out-of-bounds access.

---
 drivers/input/tablet/gtco.c |   17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

@@ -230,13 +230,17 @@ static void parse_hid_report_descriptor(
 
 	/* Walk  this report and pull out the info we need */
 	while (i < length) {
-		prefix = report[i];
-
-		/* Skip over prefix */
-		i++;
+		prefix = report[i++];
 
 		/* Determine data size and save the data in the proper variable */
-		size = PREF_SIZE(prefix);
+		size = (1U << PREF_SIZE(prefix)) >> 1;
+		if (i + size > length) {
+			dev_err(ddev,
+				"Not enough data (need %d, have %d)\n",
+				i + size, length);
+			break;
+		}
+
 		switch (size) {
 		case 1:
 			data = report[i];

@@ -244,8 +248,7 @@ static void parse_hid_report_descriptor(
 		case 2:
 			data16 = get_unaligned_le16(&report[i]);
 			break;
-		case 3:
-			size = 4;
+		case 4:
 			data32 = get_unaligned_le32(&report[i]);
 			break;
 		}

Patches currently in stable-queue which might be from [email protected] are

queue-4.13/input-elan_i2c-add-elan0611-to-the-acpi-table.patch queue-4.13/input-gtco-fix-potential-out-of-bound-access.patch