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@xxxxxxxxxx>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
---
drivers/input/tablet/gtco.c | 24 +++++++++++++++++-------
1 file changed, 17 insertions(+), 7 deletions(-)
diff --git a/drivers/input/tablet/gtco.c b/drivers/input/tablet/gtco.c
index b796e891e2ee..0351203b8c24 100644
--- a/drivers/input/tablet/gtco.c
+++ b/drivers/input/tablet/gtco.c
@@ -230,13 +230,24 @@ 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);
+ if (PREF_SIZE(prefix) < 1) {
+ dev_err(ddev,
+ "Invalid size %d in element at offset %d\n",
+ PREF_SIZE(prefix), i);
+ break;
+ }
+
+ 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 +255,7 @@ 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;
}
--
2.15.0.rc0.271.g36b669edcc-goog
--
Dmitry
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