From 52f65e35c2b85908fa66cfc265be4e3fd88744a3 Mon Sep 17 00:00:00 2001 From: Dmitry Torokhov Date: Mon, 23 Oct 2017 16:46:00 -0700 Subject: [PATCH] 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 Reviewed-by: Andrey Konovalov Signed-off-by: Dmitry Torokhov Signed-off-by: Greg Kroah-Hartman --- 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 abf09ac42ce43e..339a0e2d2f862e 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; }