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authorDmitry Torokhov <dmitry.torokhov@gmail.com>2017-10-23 16:46:00 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-11-02 09:54:48 +0100
commit8d3736faa7f7e438fab0cd28a31c0dc4eea552b8 (patch)
tree192a8f11d4ad9b53f300049efff7b8674b95e79c
parentecf572cb4f8d954b0085231c9ab310b1614e3808 (diff)
Input: gtco - fix potential out-of-bound access
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. Reported-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/input/tablet/gtco.c17
1 files 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;
}