wifi: ath12k: Fix buffer overflow when scanning with extraie

If cfg80211 is providing extraie's for a scanning process then ath12k will
copy that over to the firmware. The extraie.len is a 32 bit value in struct
element_info and describes the amount of bytes for the vendor information
elements.

The problem is the allocation of the buffer. It has to align the TLV
sections by 4 bytes. But the code was using an u8 to store the newly
calculated length of this section (with alignment). And the new
calculated length was then used to allocate the skbuff. But the actual
code to copy in the data is using the extraie.len and not the calculated
"aligned" length.

The length of extraie with IEEE80211_HW_SINGLE_SCAN_ON_ALL_BANDS enabled
was 264 bytes during tests with a wifi card. But it only allocated 8
bytes (264 bytes % 256) for it. As consequence, the code to memcpy the
extraie into the skb was then just overwriting data after skb->end. Things
like shinfo were therefore corrupted. This could usually be seen by a crash
in skb_zcopy_clear which tried to call a ubuf_info callback (using a bogus
address).

Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0-03427-QCAHMTSWPL_V1.0_V2.0_SILICONZ-1.15378.4
Signed-off-by: Wen Gong <quic_wgong@quicinc.com>
Link: https://lore.kernel.org/r/20230809081241.32765-1-quic_wgong@quicinc.comSigned-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/ath/ath12k/wmi.c

@@ -2144,8 +2144,7 @@ int ath12k_wmi_send_scan_start_cmd(struct ath12k *ar,
 	struct wmi_tlv *tlv;
 	void *ptr;
 	int i, ret, len;
-	u32 *tmp_ptr;
-	u8 extraie_len_with_pad = 0;
+	u32 *tmp_ptr, extraie_len_with_pad = 0;
 	struct ath12k_wmi_hint_short_ssid_arg *s_ssid = NULL;
 	struct ath12k_wmi_hint_bssid_arg *hint_bssid = NULL;