From a50829479f58416a013a4ccca791336af3c584c7 Mon Sep 17 00:00:00 2001
From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Date: Mon, 23 Oct 2017 16:46:00 -0700
Subject: [PATCH] Input: gtco - fix potential out-of-bound access
Patch-mainline: v4.14-rc7
References: bsc#1067085 CVE-2017-16649
Git-commit: a50829479f58416a013a4ccca791336af3c584c7
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.
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
drivers/input/tablet/gtco.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)
diff --git a/drivers/input/tablet/gtco.c b/drivers/input/tablet/gtco.c
index b796e891e2ee..4b8b9d7aa75e 100644
--- a/drivers/input/tablet/gtco.c
+++ b/drivers/input/tablet/gtco.c
@@ -230,13 +230,17 @@ static void parse_hid_report_descriptor(struct gtco *device, char * report,
/* 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(struct gtco *device, char * report,
case 2:
data16 = get_unaligned_le16(&report[i]);
break;
- case 3:
- size = 4;
+ case 4:
data32 = get_unaligned_le32(&report[i]);
break;
}
--
2.13.6