iwlwifi: mvm: assure no overflows occur while reading otp

Just in case sizes change in the OTP without proper SW
updating, an additional check is inserted when reading OTP
sections to assure no overflows occur.
Signed-off-by: Liad Kaufman <liad.kaufman@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>

drivers/net/wireless/iwlwifi/mvm/nvm.c

@@ -221,7 +221,7 @@ static int iwl_nvm_write_section(struct iwl_mvm *mvm, u16 section,
  * without overflowing, so no check is needed.
  */
 static int iwl_nvm_read_section(struct iwl_mvm *mvm, u16 section,
-				u8 *data)
+				u8 *data, u32 size_read)
 {
 	u16 length, offset = 0;
 	int ret;
@@ -233,6 +233,13 @@ static int iwl_nvm_read_section(struct iwl_mvm *mvm, u16 section,
 
 	/* Read the NVM until exhausted (reading less than requested) */
 	while (ret == length) {
+		/* Check no memory assumptions fail and cause an overflow */
+		if ((size_read + offset + length) >
+		    mvm->cfg->base_params->eeprom_size) {
+			IWL_ERR(mvm, "EEPROM size is too small for NVM\n");
+			return -ENOBUFS;
+		}
+
 		ret = iwl_nvm_read_chunk(mvm, section, offset, length, data);
 		if (ret < 0) {
 			IWL_DEBUG_EEPROM(mvm->trans->dev,
@@ -470,6 +477,7 @@ int iwl_mvm_load_nvm_to_nic(struct iwl_mvm *mvm)
 int iwl_nvm_init(struct iwl_mvm *mvm, bool read_nvm_from_nic)
 {
 	int ret, section;
+	u32 size_read = 0;
 	u8 *nvm_buffer, *temp;
 
 	if (WARN_ON_ONCE(mvm->cfg->nvm_hw_section_num >= NVM_MAX_NUM_SECTIONS))
@@ -486,9 +494,11 @@ int iwl_nvm_init(struct iwl_mvm *mvm, bool read_nvm_from_nic)
 			return -ENOMEM;
 		for (section = 0; section < NVM_MAX_NUM_SECTIONS; section++) {
 			/* we override the constness for initial read */
-			ret = iwl_nvm_read_section(mvm, section, nvm_buffer);
+			ret = iwl_nvm_read_section(mvm, section, nvm_buffer,
+						   size_read);
 			if (ret < 0)
 				continue;
+			size_read += ret;
 			temp = kmemdup(nvm_buffer, ret, GFP_KERNEL);
 			if (!temp) {
 				ret = -ENOMEM;