wifi: ath12k: Fix buffer overflow in debugfs

[ Upstream commit 8c7a503 ]

If the user tries to write more than 32 bytes then it results in memory
corruption.  Fortunately, this is debugfs so it's limited to root users.

Fixes: 3f73c24 ("wifi: ath12k: Add support to enable debugfs_htt_stats")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Vasanthakumar Thiagarajan <vasanthakumar.thiagarajan@oss.qualcomm.com>
Link: https://patch.msgid.link/35daefbd-d493-41d9-b192-96177d521b40@stanley.mountain
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: Dan Carpenter

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

@@ -1646,6 +1646,9 @@ static ssize_t ath12k_write_htt_stats_type(struct file *file,
 	const int size = 32;
 	int num_args;
 
+	if (count > size)
+		return -EINVAL;
+
 	char *buf __free(kfree) = kzalloc(size, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;