[PATCH v2 3/3] wifi: wcn36xx: fix OOB read from short trigger BA firmware response

[Tristan Madani <tristmd@gmail.com>]

From: Tristan Madani <tristan@talencesecurity.com>

The firmware response length is only checked against sizeof(*rsp) (20
bytes), but when candidate_cnt >= 1, a 22-byte candidate struct is read
at buf + 20 without verifying the response contains it. This causes an
out-of-bounds read of stale heap data, corrupting the BA session state.

Add validation that the response includes the candidate data.

Fixes: 16be1ac55944 ("wcn36xx: Parse trigger_ba response properly")
Signed-off-by: Tristan Madani <tristan@talencesecurity.com>
---
drivers/net/wireless/ath/wcn36xx/smd.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/wireless/ath/wcn36xx/smd.c b/drivers/net/wireless/ath/wcn36xx/smd.c
index XXXXXXX..XXXXXXX 100644
--- a/drivers/net/wireless/ath/wcn36xx/smd.c
+++ b/drivers/net/wireless/ath/wcn36xx/smd.c
@@ -2599,6 +2599,9 @@ static int wcn36xx_smd_trigger_ba_rsp(void *buf, int len, struct add_ba_info *ba
 	if (rsp->candidate_cnt < 1)
 		return rsp->status ? rsp->status : -EINVAL;

+	if (len < sizeof(*rsp) + sizeof(*candidate))
+		return -EINVAL;
+
 	candidate = (struct wcn36xx_hal_trigger_ba_rsp_candidate *)(buf + sizeof(*rsp));

 	for (i = 0; i < STACFG_MAX_TC; i++) {