iwlwifi: dvm: don't call << operator with a negative value
In https://bugzilla.kernel.org/show_bug.cgi?id=177341 Bob
reported a UBSAN WARNING on rs.c.
Undefined behaviour in drivers/net/wireless/intel/iwlwifi/dvm/rs.c:746:18
This because
i = index - 1;
for (mask = (1 << i); i >= 0; i--, mask >>= 1)
is unsafe: i could be negative and hence we can call <<
on a negative value.
This bug doesn't have any real impact since the condition
of the for loop will prevent any usage of mask.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=177341
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
diff --git a/drivers/net/wireless/intel/iwlwifi/dvm/rs.c b/drivers/net/wireless/intel/iwlwifi/dvm/rs.c
index 710dbbe..ff44ebc 100644
--- a/drivers/net/wireless/intel/iwlwifi/dvm/rs.c
+++ b/drivers/net/wireless/intel/iwlwifi/dvm/rs.c
@@ -740,7 +740,10 @@ static u16 rs_get_adjacent_rate(struct iwl_priv *priv, u8 index, u16 rate_mask,
/* Find the previous rate that is in the rate mask */
i = index - 1;
- for (mask = (1 << i); i >= 0; i--, mask >>= 1) {
+ if (i >= 0)
+ mask = BIT(i);
+
+ for (; i >= 0; i--, mask >>= 1) {
if (rate_mask & mask) {
low = i;
break;