This patch is driven by a static checker warning.
The ttusb_process_muxpack() function is only called from
ttusb_process_frame(). Before calling, it verifies that len >= 2. The
problem is that len == 2 is not valid and would lead to an array
underflow.
Odd number values for len are also invalid and would lead to reading
past the end of the array.
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
---
v2: Moved the check from the caller into the function. Added a check
for odd values. Added an error message. Increment the numinvalid
counter.
diff --git a/drivers/media/usb/ttusb-budget/dvb-ttusb-budget.c b/drivers/media/usb/ttusb-budget/dvb-ttusb-budget.c
index 5b682cc..e407185 100644
--- a/drivers/media/usb/ttusb-budget/dvb-ttusb-budget.c
+++ b/drivers/media/usb/ttusb-budget/dvb-ttusb-budget.c
@@ -561,6 +561,13 @@ static void ttusb_process_muxpack(struct ttusb *ttusb, const u8 * muxpack,
{
u16 csum = 0, cc;
int i;
+
+ if (len < 4 || len & 0x1) {
+ pr_warn("%s: muxpack has invalid len %d\n", __func__, len);
+ numinvalid++;
+ return;
+ }
+
for (i = 0; i < len; i += 2)
csum ^= le16_to_cpup((__le16 *) (muxpack + i));
if (csum) {
--
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