Subject: [PATCH] ath9k_htc: fix uninit value bugs

From: Pavel Skripkin <[email-masked]>
Date: Sat, 15 Jan 2022 15:27:33 +0300

Syzbot reported 2 KMSAN bugs in ath9k. All of them are caused by missing
field initialization.

In htc_connect_service() svc_meta_len and pad are not initialized. Based
on code it looks like in current skb there is no service data, so simply
initialize svc_meta_len to 0.

htc_issue_send() does not initialize htc_frame_hdr::control array. Based
on firmware code, it will initialize it by itself, so simply zero whole
array to make KMSAN happy

Fail logs:

BUG: KMSAN: kernel-usb-infoleak in usb_submit_urb+0x6c1/0x2aa0 drivers/usb/core/urb.c:430
 usb_submit_urb+0x6c1/0x2aa0 drivers/usb/core/urb.c:430
 hif_usb_send_regout drivers/net/wireless/ath/ath9k/hif_usb.c:127 [inline]
 hif_usb_send+0x5f0/0x16f0 drivers/net/wireless/ath/ath9k/hif_usb.c:479
 htc_issue_send drivers/net/wireless/ath/ath9k/htc_hst.c:34 [inline]
 htc_connect_service+0x143e/0x1960 drivers/net/wireless/ath/ath9k/htc_hst.c:275
...

Uninit was created at:
 slab_post_alloc_hook mm/slab.h:524 [inline]
 slab_alloc_node mm/slub.c:3251 [inline]
 __kmalloc_node_track_caller+0xe0c/0x1510 mm/slub.c:4974
 kmalloc_reserve net/core/skbuff.c:354 [inline]
 __alloc_skb+0x545/0xf90 net/core/skbuff.c:426
 alloc_skb include/linux/skbuff.h:1126 [inline]
 htc_connect_service+0x1029/0x1960 drivers/net/wireless/ath/ath9k/htc_hst.c:258
...

Bytes 4-7 of 18 are uninitialized
Memory access of size 18 starts at ffff888027377e00

BUG: KMSAN: kernel-usb-infoleak in usb_submit_urb+0x6c1/0x2aa0 drivers/usb/core/urb.c:430
 usb_submit_urb+0x6c1/0x2aa0 drivers/usb/core/urb.c:430
 hif_usb_send_regout drivers/net/wireless/ath/ath9k/hif_usb.c:127 [inline]
 hif_usb_send+0x5f0/0x16f0 drivers/net/wireless/ath/ath9k/hif_usb.c:479
 htc_issue_send drivers/net/wireless/ath/ath9k/htc_hst.c:34 [inline]
 htc_connect_service+0x143e/0x1960 drivers/net/wireless/ath/ath9k/htc_hst.c:275
...

Uninit was created at:
 slab_post_alloc_hook mm/slab.h:524 [inline]
 slab_alloc_node mm/slub.c:3251 [inline]
 __kmalloc_node_track_caller+0xe0c/0x1510 mm/slub.c:4974
 kmalloc_reserve net/core/skbuff.c:354 [inline]
 __alloc_skb+0x545/0xf90 net/core/skbuff.c:426
 alloc_skb include/linux/skbuff.h:1126 [inline]
 htc_connect_service+0x1029/0x1960 drivers/net/wireless/ath/ath9k/htc_hst.c:258
...

Bytes 16-17 of 18 are uninitialized
Memory access of size 18 starts at ffff888027377e00

Fixes: fb9987d0f748 ("ath9k_htc: Support for AR9271 chipset.")
Reported-by: [email-masked]
Signed-off-by: Pavel Skripkin <[email-masked]>
---
 drivers/net/wireless/ath/ath9k/htc_hst.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/wireless/ath/ath9k/htc_hst.c b/drivers/net/wireless/ath/ath9k/htc_hst.c
index 510e61e97dbc..994ec48b2f66 100644
--- a/drivers/net/wireless/ath/ath9k/htc_hst.c
+++ b/drivers/net/wireless/ath/ath9k/htc_hst.c
@@ -30,6 +30,7 @@ static int htc_issue_send(struct htc_target *target, struct sk_buff* skb,
 	hdr->endpoint_id = epid;
 	hdr->flags = flags;
 	hdr->payload_len = cpu_to_be16(len);
+	memset(hdr->control, 0, sizeof(hdr->control));
 
 	status = target->hif->send(target->hif_dev, endpoint->ul_pipeid, skb);
 
@@ -272,6 +273,10 @@ int htc_connect_service(struct htc_target *target,
 	conn_msg->dl_pipeid = endpoint->dl_pipeid;
 	conn_msg->ul_pipeid = endpoint->ul_pipeid;
 
+	/* To prevent infoleak */
+	conn_msg->svc_meta_len = 0;
+	conn_msg->pad = 0;
+
 	ret = htc_issue_send(target, skb, skb->len, 0, ENDPOINT0);
 	if (ret)
 		goto err;
-- 
2.34.1