[PATCH v2 5/6] wifi: mwifiex: fix OOB read from firmware intf_num in multichannel event

[Tristan Madani <tristmd@gmail.com>]

From: Tristan Madani <tristan@talencesecurity.com>

The firmware-controlled intf_num is used to iterate the flexible array
bss_type_numlist[] without checking it against the TLV data length. An
inflated value causes out-of-bounds reads past the TLV data.

Clamp intf_num to the available TLV data.

Fixes: 8d6b538a5eac ("mwifiex: handle multichannel event")
Signed-off-by: Tristan Madani <tristan@talencesecurity.com>
---
drivers/net/wireless/marvell/mwifiex/sta_event.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/net/wireless/marvell/mwifiex/sta_event.c b/drivers/net/wireless/marvell/mwifiex/sta_event.c
index XXXXXXX..XXXXXXX 100644
--- a/drivers/net/wireless/marvell/mwifiex/sta_event.c
+++ b/drivers/net/wireless/marvell/mwifiex/sta_event.c
@@ -450,7 +450,15 @@ void mwifiex_process_multi_chan_event(struct mwifiex_private *priv,
 		grp_info = (struct mwifiex_ie_types_mc_group_info *)tlv;

 		intf_num = grp_info->intf_num;
+		{
+			u16 fixed_len = sizeof(*grp_info) -
+					sizeof(grp_info->header);
+			if (tlv_len < fixed_len ||
+			    intf_num > tlv_len - fixed_len)
+				intf_num = 0;
+		}
+
 		for (i = 0; i < intf_num; i++) {
 			bss_type = grp_info->bss_type_numlist[i] >> 4;