mwifiex: fix invalid memory access in mwifiex_ret_tx_rate_cfg()

As tlv_buf_len is decremented at the end of the loop, we may have
accessed invalid memory in the last iteration.
Modify the while condition and add a break statement at the
begining of the loop to fix the problem.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/drivers/net/wireless/mwifiex/sta_cmdresp.c b/drivers/net/wireless/mwifiex/sta_cmdresp.c
index 5edea4d..2675ca7 100644 (file)
--- a/drivers/net/wireless/mwifiex/sta_cmdresp.c
+++ b/drivers/net/wireless/mwifiex/sta_cmdresp.c
@@ -274,17 +274,20 @@ static int mwifiex_ret_tx_rate_cfg(struct mwifiex_private *priv,
        struct host_cmd_ds_tx_rate_cfg *rate_cfg = &resp->params.tx_rate_cfg;
        struct mwifiex_rate_scope *rate_scope;
        struct mwifiex_ie_types_header *head;
-       u16 tlv, tlv_buf_len;
+       u16 tlv, tlv_buf_len, tlv_buf_left;
        u8 *tlv_buf;
        u32 i;
 
-       tlv_buf = ((u8 *)rate_cfg) +
-                       sizeof(struct host_cmd_ds_tx_rate_cfg);
-       tlv_buf_len = le16_to_cpu(*(__le16 *) (tlv_buf + sizeof(u16)));
+       tlv_buf = ((u8 *)rate_cfg) + sizeof(struct host_cmd_ds_tx_rate_cfg);
+       tlv_buf_left = le16_to_cpu(resp->size) - S_DS_GEN - sizeof(*rate_cfg);
 
-       while (tlv_buf && tlv_buf_len > 0) {
-               tlv = (*tlv_buf);
-               tlv = tlv | (*(tlv_buf + 1) << 8);
+       while (tlv_buf_left >= sizeof(*head)) {
+               head = (struct mwifiex_ie_types_header *)tlv_buf;
+               tlv = le16_to_cpu(head->type);
+               tlv_buf_len = le16_to_cpu(head->len);
+
+               if (tlv_buf_left < (sizeof(*head) + tlv_buf_len))
+                       break;
 
                switch (tlv) {
                case TLV_TYPE_RATE_SCOPE:
@@ -304,9 +307,8 @@ static int mwifiex_ret_tx_rate_cfg(struct mwifiex_private *priv,
                        /* Add RATE_DROP tlv here */
                }
 
-               head = (struct mwifiex_ie_types_header *) tlv_buf;
-               tlv_buf += le16_to_cpu(head->len) + sizeof(*head);
-               tlv_buf_len -= le16_to_cpu(head->len);
+               tlv_buf += (sizeof(*head) + tlv_buf_len);
+               tlv_buf_left -= (sizeof(*head) + tlv_buf_len);
        }
 
        priv->is_data_rate_auto = mwifiex_is_rate_auto(priv);