[PATCH 3.16 21/61] mwifiex: Fix possible buffer overflows in mwifiex_cmd_append_vsie_tlv()

[Ben Hutchings]

3.16.85-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Qing Xu <m1s5p6688@xxxxxxxxx>

commit b70261a288ea4d2f4ac7cd04be08a9f0f2de4f4d upstream.

mwifiex_cmd_append_vsie_tlv() calls memcpy() without checking
the destination size may trigger a buffer overflower,
which a local user could use to cause denial of service
or the execution of arbitrary code.
Fix it by putting the length check before calling memcpy().

Signed-off-by: Qing Xu <m1s5p6688@xxxxxxxxx>
Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxxxxxx>
[bwh: Backported to 3.16:
 - Use dev_info() instead of mwifiex_dbg()
 - Adjust filename]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/net/wireless/mwifiex/scan.c | 7 +++++++
 1 file changed, 7 insertions(+)

--- a/drivers/net/wireless/mwifiex/scan.c
+++ b/drivers/net/wireless/mwifiex/scan.c
@@ -2267,6 +2267,13 @@ mwifiex_cmd_append_vsie_tlv(struct mwifi
 			vs_param_set->header.len =
 				cpu_to_le16((((u16) priv->vs_ie[id].ie[1])
 				& 0x00FF) + 2);
+			if (le16_to_cpu(vs_param_set->header.len) >
+				MWIFIEX_MAX_VSIE_LEN) {
+				dev_info(priv->adapter->dev,
+					 "Invalid param length!\n");
+				break;
+			}
+
 			memcpy(vs_param_set->ie, priv->vs_ie[id].ie,
 			       le16_to_cpu(vs_param_set->header.len));
 			*buffer += le16_to_cpu(vs_param_set->header.len) +