[PATCH RFC ath-next 1/2] wifi: ath11k: bound READY MAC address array reads

[John Macias via B4 Relay <devnull+dencity7.gmail.com@kernel.org>]

From: John Macias <dencity7@gmail.com>

The READY event carries a fixed record whose num_extra_mac_addr field
advertises how many per-radio MAC addresses follow, and a separate
WMI_TAG_ARRAY_FIXED_STRUCT TLV holding that array. The TLV iterator
only ensures that the array TLV fits inside the event;
ath11k_wmi_tlv_rdy_parse() then copies one address per radio without
checking that the array really holds num_radios entries.

If firmware advertises at least num_radios extra addresses but sends a
shorter array, for example two radios with an eight-byte array, the second
ether_addr_copy() reads past the end of the TLV value.

Check the array length against num_radios before copying. When it is too
short, warn and leave pdevs_macaddr_valid unset, so the driver falls back
to deriving the per-radio addresses as it does when no array is provided,
instead of failing READY processing.

Found by code review while bringing up a device with older firmware; a
userspace harness that includes the unmodified parser reports a 6-byte
heap-buffer-overflow read under AddressSanitizer for this input, and
the fixed parser passes. Compile tested only (ath-next, W=1).

Fixes: d5c65159f289 ("ath11k: driver for Qualcomm IEEE 802.11ax devices")
Assisted-by: LLM
Signed-off-by: John Macias <dencity7@gmail.com>
---
 drivers/net/wireless/ath/ath11k/wmi.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/wireless/ath/ath11k/wmi.c b/drivers/net/wireless/ath/ath11k/wmi.c
index 08fd6795ed..6ae4e881f8 100644
--- a/drivers/net/wireless/ath/ath11k/wmi.c
+++ b/drivers/net/wireless/ath/ath11k/wmi.c
@@ -7330,6 +7330,12 @@ static int ath11k_wmi_tlv_rdy_parse(struct ath11k_base *ab, u16 tag, u16 len,
 		if (!(ab->num_radios > 1 && num_mac_addr >= ab->num_radios))
 			break;
 
+		if (len < ab->num_radios * sizeof(*addr_list)) {
+			ath11k_warn(ab, "ready event mac address array too short: %u bytes for %d radios\n",
+				    len, ab->num_radios);
+			break;
+		}
+
 		for (i = 0; i < ab->num_radios; i++) {
 			pdev = &ab->pdevs[i];
 			ether_addr_copy(pdev->mac_addr, addr_list[i].addr);

-- 
2.47.3