[PATCH AUTOSEL 6.0 20/77] wifi: ath9k: avoid uninit memory read in ath9k_htc_rx_msg()

Sasha Levin
2022-10-09T22:10:44Z

From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

[ Upstream commit b383e8abed41cc6ff1a3b34de75df9397fa4878c ]

syzbot is reporting uninit value at ath9k_htc_rx_msg() [1], for
ioctl(USB_RAW_IOCTL_EP_WRITE) can call ath9k_hif_usb_rx_stream() with
pkt_len = 0 but ath9k_hif_usb_rx_stream() uses
__dev_alloc_skb(pkt_len + 32, GFP_ATOMIC) based on an assumption that
pkt_len is valid. As a result, ath9k_hif_usb_rx_stream() allocates skb
with uninitialized memory and ath9k_htc_rx_msg() is reading from
uninitialized memory.

Since bytes accessed by ath9k_htc_rx_msg() is not known until
ath9k_htc_rx_msg() is called, it would be difficult to check minimal valid
pkt_len at "if (pkt_len > 2 * MAX_RX_BUF_SIZE) {" line in
ath9k_hif_usb_rx_stream().

We have two choices. One is to workaround by adding __GFP_ZERO so that
ath9k_htc_rx_msg() sees 0 if pkt_len is invalid. The other is to let
ath9k_htc_rx_msg() validate pkt_len before accessing. This patch chose
the latter.

Note that I'm not sure threshold condition is correct, for I can't find
details on possible packet length used by this protocol.

Link: https://syzkaller.appspot.com/bug?extid=2ca247c2d60c7023de7f [1]
Reported-by: syzbot <syzbot+2ca247c2d60c7023de7f@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/7acfa1be-4b5c-b2ce-de43-95b0593fb3e5@I-love.SAKURA.ne.jp
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/wireless/ath/ath9k/htc_hst.c | 43 +++++++++++++++---------
1 file changed, 28 insertions(+), 15 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/htc_hst.c b/drivers/net/wireless/ath/ath9k/htc_hst.c
index 994ec48b2f66..ca05b07a45e6 100644
--- a/drivers/net/wireless/ath/ath9k/htc_hst.c
+++ b/drivers/net/wireless/ath/ath9k/htc_hst.c
@@ -364,33 +364,27 @@ void ath9k_htc_txcompletion_cb(struct htc_target *htc_handle,
}

static void ath9k_htc_fw_panic_report(struct htc_target *htc_handle,
- struct sk_buff *skb)
+ struct sk_buff *skb, u32 len)
{
uint32_t *pattern = (uint32_t *)skb->data;

- switch (*pattern) {
- case 0x33221199:
- {
+ if (*pattern == 0x33221199 && len >= sizeof(struct htc_panic_bad_vaddr)) {
struct htc_panic_bad_vaddr *htc_panic;
htc_panic = (struct htc_panic_bad_vaddr *) skb->data;
dev_err(htc_handle->dev, "ath: firmware panic! "
"exccause: 0x%08x; pc: 0x%08x; badvaddr: 0x%08x.\n",
htc_panic->exccause, htc_panic->pc,
htc_panic->badvaddr);
- break;
- }
- case 0x33221299:
- {
+ return;
+ }
+ if (*pattern == 0x33221299) {
struct htc_panic_bad_epid *htc_panic;
htc_panic = (struct htc_panic_bad_epid *) skb->data;
dev_err(htc_handle->dev, "ath: firmware panic! "
"bad epid: 0x%08x\n", htc_panic->epid);
- break;
- }
- default:
- dev_err(htc_handle->dev, "ath: unknown panic pattern!\n");
- break;
+ return;
}
+ dev_err(htc_handle->dev, "ath: unknown panic pattern!\n");
}

/*
@@ -411,16 +405,26 @@ void ath9k_htc_rx_msg(struct htc_target *htc_handle,
if (!htc_handle || !skb)
return;

+ /* A valid message requires len >= 8.
+ *
+ * sizeof(struct htc_frame_hdr) == 8
+ * sizeof(struct htc_ready_msg) == 8
+ * sizeof(struct htc_panic_bad_vaddr) == 16
+ * sizeof(struct htc_panic_bad_epid) == 8
+ */
+ if (unlikely(len < sizeof(struct htc_frame_hdr)))
+ goto invalid;
htc_hdr = (struct htc_frame_hdr *) skb->data;
epid = htc_hdr->endpoint_id;

if (epid == 0x99) {
- ath9k_htc_fw_panic_report(htc_handle, skb);
+ ath9k_htc_fw_panic_report(htc_handle, skb, len);
kfree_skb(skb);
return;
}

if (epid < 0 || epid >= ENDPOINT_MAX) {
+invalid:
if (pipe_id != USB_REG_IN_PIPE)
dev_kfree_skb_any(skb);
else
@@ -432,21 +436,30 @@ void ath9k_htc_rx_msg(struct htc_target *htc_handle,

/* Handle trailer */
if (htc_hdr->flags & HTC_FLAGS_RECV_TRAILER) {
- if (be32_to_cpu(*(__be32 *) skb->data) == 0x00C60000)
+ if (be32_to_cpu(*(__be32 *) skb->data) == 0x00C60000) {
/* Move past the Watchdog pattern */
htc_hdr = (struct htc_frame_hdr *)(skb->data + 4);
+ len -= 4;
+ }
}

/* Get the message ID */
+ if (unlikely(len < sizeof(struct htc_frame_hdr) + sizeof(__be16)))
+ goto invalid;
msg_id = (__be16 *) ((void *) htc_hdr +
sizeof(struct htc_frame_hdr));

/* Now process HTC messages */
switch (be16_to_cpu(*msg_id)) {
case HTC_MSG_READY_ID:
+ if (unlikely(len < sizeof(struct htc_ready_msg)))
+ goto invalid;
htc_process_target_rdy(htc_handle, htc_hdr);
break;
case HTC_MSG_CONNECT_SERVICE_RESPONSE_ID:
+ if (unlikely(len < sizeof(struct htc_frame_hdr) +
+ sizeof(struct htc_conn_svc_rspmsg)))
+ goto invalid;
htc_process_conn_rsp(htc_handle, htc_hdr);
break;
default:
--
2.35.1