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

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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>
This commit is contained in:
Dmitry Torokhov 2017-10-23 16:46:00 -07:00
parent 57a95b4186
commit a50829479f
1 changed files with 10 additions and 7 deletions
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17
drivers/input/tablet/gtco.c
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@ -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;
}