[v5,1/8] ath10k: adjust skb length in ath10k_sdio_mbox_rx_packet

Commit Message

Wen Gong Sept. 5, 2019, 10:38 a.m. UTC

From: Nicolas Boichat <[e-mail]>

When the FW bundles multiple packets, pkt->act_len may be incorrect
as it refers to the first packet only (however, the FW will only
bundle packets that fit into the same pkt->alloc_len).

Before this patch, the skb length would be set (incorrectly) to
pkt->act_len in ath10k_sdio_mbox_rx_packet, and then later manually
adjusted in ath10k_sdio_mbox_rx_process_packet.

The first problem is that ath10k_sdio_mbox_rx_process_packet does not
use proper skb_put commands to adjust the length (it directly changes
skb->len), so we end up with a mismatch between skb->head + skb->tail
and skb->data + skb->len. This is quite serious, and causes corruptions
in the TCP stack, as the stack tries to coalesce packets, and relies
on skb->tail being correct (that is, skb_tail_pointer must point to
the first byte_after_ the data).

Instead of re-adjusting the size in ath10k_sdio_mbox_rx_process_packet,
this moves the code to ath10k_sdio_mbox_rx_packet, and also add a
bounds check, as skb_put would crash the kernel if not enough space is
available.

Tested with QCA6174 SDIO with firmware
WLAN.RMH.4.4.1-00007-QCARMSWP-1.

Fixes: 8530b4e7b22bc3b ("ath10k: sdio: set skb len for all rx packets")
Signed-off-by: Nicolas Boichat <[e-mail]>
Signed-off-by: Wen Gong <[e-mail]>
---
v2: no this patch
v3: new added
v4: change commit log
v5: no change
 drivers/net/wireless/ath/ath10k/sdio.c | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

Comments

Kalle Valo Sept. 12, 2019, 1:46 p.m. UTC | #1

Wen Gong <[e-mail]> writes:

> From: Nicolas Boichat <[e-mail]>
>
> When the FW bundles multiple packets, pkt->act_len may be incorrect
> as it refers to the first packet only (however, the FW will only
> bundle packets that fit into the same pkt->alloc_len).
>
> Before this patch, the skb length would be set (incorrectly) to
> pkt->act_len in ath10k_sdio_mbox_rx_packet, and then later manually
> adjusted in ath10k_sdio_mbox_rx_process_packet.
>
> The first problem is that ath10k_sdio_mbox_rx_process_packet does not
> use proper skb_put commands to adjust the length (it directly changes
> skb->len), so we end up with a mismatch between skb->head + skb->tail
> and skb->data + skb->len. This is quite serious, and causes corruptions
> in the TCP stack, as the stack tries to coalesce packets, and relies
> on skb->tail being correct (that is, skb_tail_pointer must point to
> the first byte_after_ the data).
>
> Instead of re-adjusting the size in ath10k_sdio_mbox_rx_process_packet,
> this moves the code to ath10k_sdio_mbox_rx_packet, and also add a
> bounds check, as skb_put would crash the kernel if not enough space is
> available.
>
> Tested with QCA6174 SDIO with firmware
> WLAN.RMH.4.4.1-00007-QCARMSWP-1.
>
> Fixes: 8530b4e7b22bc3b ("ath10k: sdio: set skb len for all rx packets")
> Signed-off-by: Nicolas Boichat <[e-mail]>
> Signed-off-by: Wen Gong <[e-mail]>

[...]

> @@ -632,13 +627,29 @@ static int ath10k_sdio_mbox_rx_packet(struct ath10k *ar,
>  {
>  	struct ath10k_sdio *ar_sdio = ath10k_sdio_priv(ar);
>  	struct sk_buff *skb = pkt->skb;
> +	struct ath10k_htc_hdr *htc_hdr;
>  	int ret;
>  
>  	ret = ath10k_sdio_readsb(ar, ar_sdio->mbox_info.htc_addr,
>  				 skb->data, pkt->alloc_len);
> +
> +	if (!ret) {
> +		/* Update actual length. The original length may be incorrect,
> +		 * as the FW will bundle multiple packets as long as their sizes
> +		 * fit within the same aligned length (pkt->alloc_len).
> +		 */
> +		htc_hdr = (struct ath10k_htc_hdr *)skb->data;
> +		pkt->act_len = le16_to_cpu(htc_hdr->len) + sizeof(*htc_hdr);
> +		if (pkt->act_len <= pkt->alloc_len) {
> +			skb_put(skb, pkt->act_len);
> +		} else {
> +			ath10k_warn(ar, "rx packet too large (%zu > %zu)\n",
> +				    pkt->act_len, pkt->alloc_len);
> +			ret = -EMSGSIZE;
> +		}
> +	}
> +
>  	pkt->status = ret;
> -	if (!ret)
> -		skb_put(skb, pkt->act_len);
>  
>  	return ret;
>  }

I simplified the error handling in this function to follow the ath10k
style, please check carefully that I didn't create any bugs:

https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git/commit/?h=pending&id=6e4d2cc5

Nicolas Boichat Sept. 12, 2019, 2:02 p.m. UTC | #2

On Thu, Sep 12, 2019 at 9:46 PM Kalle Valo <[e-mail]> wrote:
>
> Wen Gong <[e-mail]> writes:
>
> > From: Nicolas Boichat <[e-mail]>
> [...]
>
> I simplified the error handling in this function to follow the ath10k
> style, please check carefully that I didn't create any bugs:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git/commit/?h=pending&id=6e4d2cc5

Thanks, that looks right.

> --
> https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

Kalle Valo Sept. 12, 2019, 2:54 p.m. UTC | #3

Wen Gong <[e-mail]> wrote:

> When the FW bundles multiple packets, pkt->act_len may be incorrect
> as it refers to the first packet only (however, the FW will only
> bundle packets that fit into the same pkt->alloc_len).
> 
> Before this patch, the skb length would be set (incorrectly) to
> pkt->act_len in ath10k_sdio_mbox_rx_packet, and then later manually
> adjusted in ath10k_sdio_mbox_rx_process_packet.
> 
> The first problem is that ath10k_sdio_mbox_rx_process_packet does not
> use proper skb_put commands to adjust the length (it directly changes
> skb->len), so we end up with a mismatch between skb->head + skb->tail
> and skb->data + skb->len. This is quite serious, and causes corruptions
> in the TCP stack, as the stack tries to coalesce packets, and relies
> on skb->tail being correct (that is, skb_tail_pointer must point to
> the first byte_after_ the data).
> 
> Instead of re-adjusting the size in ath10k_sdio_mbox_rx_process_packet,
> this moves the code to ath10k_sdio_mbox_rx_packet, and also add a
> bounds check, as skb_put would crash the kernel if not enough space is
> available.
> 
> Tested with QCA6174 SDIO with firmware
> WLAN.RMH.4.4.1-00007-QCARMSWP-1.
> 
> Fixes: 8530b4e7b22bc3b ("ath10k: sdio: set skb len for all rx packets")
> Signed-off-by: Nicolas Boichat <[e-mail]>
> Signed-off-by: Wen Gong <[e-mail]>
> Signed-off-by: Kalle Valo <[e-mail]>

Patch applied to ath-next branch of ath.git, thanks.

b7139960832e ath10k: adjust skb length in ath10k_sdio_mbox_rx_packet

Patch

diff --git a/drivers/net/wireless/ath/ath10k/sdio.c b/drivers/net/wireless/ath/ath10k/sdio.c
index 8ed4fbd..1127e44 100644
--- a/drivers/net/wireless/ath/ath10k/sdio.c
+++ b/drivers/net/wireless/ath/ath10k/sdio.c
@@ -381,16 +381,11 @@  static int ath10k_sdio_mbox_rx_process_packet(struct ath10k *ar,
 	struct ath10k_htc_hdr *htc_hdr = (struct ath10k_htc_hdr *)skb->data;
 	bool trailer_present = htc_hdr->flags & ATH10K_HTC_FLAG_TRAILER_PRESENT;
 	enum ath10k_htc_ep_id eid;
-	u16 payload_len;
 	u8 *trailer;
 	int ret;
 
-	payload_len = le16_to_cpu(htc_hdr->len);
-	skb->len = payload_len + sizeof(struct ath10k_htc_hdr);
-
 	if (trailer_present) {
-		trailer = skb->data + sizeof(*htc_hdr) +
-			  payload_len - htc_hdr->trailer_len;
+		trailer = skb->data + skb->len - htc_hdr->trailer_len;
 
 		eid = pipe_id_to_eid(htc_hdr->eid);
 
@@ -632,13 +627,29 @@  static int ath10k_sdio_mbox_rx_packet(struct ath10k *ar,
 {
 	struct ath10k_sdio *ar_sdio = ath10k_sdio_priv(ar);
 	struct sk_buff *skb = pkt->skb;
+	struct ath10k_htc_hdr *htc_hdr;
 	int ret;
 
 	ret = ath10k_sdio_readsb(ar, ar_sdio->mbox_info.htc_addr,
 				 skb->data, pkt->alloc_len);
+
+	if (!ret) {
+		/* Update actual length. The original length may be incorrect,
+		 * as the FW will bundle multiple packets as long as their sizes
+		 * fit within the same aligned length (pkt->alloc_len).
+		 */
+		htc_hdr = (struct ath10k_htc_hdr *)skb->data;
+		pkt->act_len = le16_to_cpu(htc_hdr->len) + sizeof(*htc_hdr);
+		if (pkt->act_len <= pkt->alloc_len) {
+			skb_put(skb, pkt->act_len);
+		} else {
+			ath10k_warn(ar, "rx packet too large (%zu > %zu)\n",
+				    pkt->act_len, pkt->alloc_len);
+			ret = -EMSGSIZE;
+		}
+	}
+
 	pkt->status = ret;
-	if (!ret)
-		skb_put(skb, pkt->act_len);
 
 	return ret;
 }