3.2.96-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Dmitry Torokhov <[email protected]> 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 <[email protected]> Reviewed-by: Andrey Konovalov <[email protected]> Signed-off-by: Dmitry Torokhov <[email protected]> [bwh: Backported to 3.2: use &device->usbdev->dev as the device for dev_err()] Signed-off-by: Ben Hutchings <[email protected]> --- drivers/input/tablet/gtco.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) --- a/drivers/input/tablet/gtco.c +++ b/drivers/input/tablet/gtco.c @@ -232,13 +232,17 @@ static void parse_hid_report_descriptor( /* 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(&device->usbdev->dev, + "Not enough data (need %d, have %d)\n", + i + size, length); + break; + } + switch (size) { case 1: data = report[i]; @@ -246,8 +250,7 @@ static void parse_hid_report_descriptor( case 2: data16 = get_unaligned_le16(&report[i]); break; - case 3: - size = 4; + case 4: data32 = get_unaligned_le32(&report[i]); break; }
