[PATCH 1/2] mwifiex: do no submit URB in suspended state

[PATCH 1/2] mwifiex: do no submit URB in suspended state

[Ganapathi Bhat]

There is a possible race between USB suspend and main thread:

1. After processing the command response, main thread will submit
rx_cmd URB back so as to process next command response, by
calling mwifiex_usb_submit_rx_urb.

2. During USB suspend, the suspend handler will check if rx_cmd
URB is pending(submitted) and if true, kill this URB.

There is a possible race between #1 and #2, where rx_cmd URB will
be submitted by main thread(#1) after the suspend handler check
in #2.

To fix this, check if device is already suspended in
mwifiex_usb_submit_rx_urb, in which case do not submit the URB.

Signed-off-by: Vidya Dharmaraju <vidyad@marvell.com>
Signed-off-by: Cathy Luo <cluo@marvell.com>
Signed-off-by: Ganapathi Bhat <gbhat@marvell.com>
---
 drivers/net/wireless/marvell/mwifiex/usb.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/wireless/marvell/mwifiex/usb.c b/drivers/net/wireless/marvell/mwifiex/usb.c
index 433c6a16..76d80fd 100644
--- a/drivers/net/wireless/marvell/mwifiex/usb.c
+++ b/drivers/net/wireless/marvell/mwifiex/usb.c
@@ -298,6 +298,13 @@ static int mwifiex_usb_submit_rx_urb(struct urb_context *ctx, int size)
 	struct mwifiex_adapter *adapter = ctx->adapter;
 	struct usb_card_rec *card = (struct usb_card_rec *)adapter->card;
 
+	if (test_bit(MWIFIEX_IS_SUSPENDED, &adapter->work_flags)) {
+		mwifiex_dbg(adapter, ERROR,
+			    "%s: card removed/suspended, EP %d rx_cmd URB submit skipped\n",
+			    __func__, ctx->ep);
+		return -1;
+	}
+
 	if (card->rx_cmd_ep != ctx->ep) {
 		ctx->skb = dev_alloc_skb(size);
 		if (!ctx->skb) {
-- 
1.9.1

[PATCH 2/2] mwifex: free rx_cmd skb in suspended state

[Ganapathi Bhat]

USB suspend handler will kill the presubmitted rx_cmd URB. This
triggers a call to the corresponding URB complete handler, which
will free the rx_cmd skb, associated with rx_cmd URB. Due to a
possible race betwen suspend handler and main thread, depicted in
'commit bfcacac6c84b ("mwifiex: do no submit URB in suspended
state")', it is possible that the rx_cmd skb will fail to get
freed. This causes a memory leak, since the resume handler will
always allocate a new rx_cmd skb.

To fix this, free the rx_cmd skb in mwifiex_usb_submit_rx_urb, if
the device is in suspended state.

Signed-off-by: Vidya Dharmaraju <vidyad@marvell.com>
Signed-off-by: Cathy Luo <cluo@marvell.com>
Signed-off-by: Ganapathi Bhat <gbhat@marvell.com>
---
 drivers/net/wireless/marvell/mwifiex/usb.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/wireless/marvell/mwifiex/usb.c b/drivers/net/wireless/marvell/mwifiex/usb.c
index 76d80fd..d445acc 100644
--- a/drivers/net/wireless/marvell/mwifiex/usb.c
+++ b/drivers/net/wireless/marvell/mwifiex/usb.c
@@ -299,6 +299,12 @@ static int mwifiex_usb_submit_rx_urb(struct urb_context *ctx, int size)
 	struct usb_card_rec *card = (struct usb_card_rec *)adapter->card;
 
 	if (test_bit(MWIFIEX_IS_SUSPENDED, &adapter->work_flags)) {
+		if (card->rx_cmd_ep == ctx->ep) {
+			mwifiex_dbg(adapter, INFO, "%s: free rx_cmd skb\n",
+				    __func__);
+			dev_kfree_skb_any(ctx->skb);
+			ctx->skb = NULL;
+		}
 		mwifiex_dbg(adapter, ERROR,
 			    "%s: card removed/suspended, EP %d rx_cmd URB submit skipped\n",
 			    __func__, ctx->ep);
-- 
1.9.1

Re: [PATCH 1/2] mwifiex: do no submit URB in suspended state

[Kalle Valo]

Ganapathi Bhat <gbhat@marvell.com> wrote:

> There is a possible race between USB suspend and main thread:
> 
> 1. After processing the command response, main thread will submit
> rx_cmd URB back so as to process next command response, by
> calling mwifiex_usb_submit_rx_urb.
> 
> 2. During USB suspend, the suspend handler will check if rx_cmd
> URB is pending(submitted) and if true, kill this URB.
> 
> There is a possible race between #1 and #2, where rx_cmd URB will
> be submitted by main thread(#1) after the suspend handler check
> in #2.
> 
> To fix this, check if device is already suspended in
> mwifiex_usb_submit_rx_urb, in which case do not submit the URB.
> 
> Signed-off-by: Vidya Dharmaraju <vidyad@marvell.com>
> Signed-off-by: Cathy Luo <cluo@marvell.com>
> Signed-off-by: Ganapathi Bhat <gbhat@marvell.com>

2 patches applied to wireless-drivers-next.git, thanks.

7bd4628c2f31 mwifiex: do no submit URB in suspended state
33a164fa8a4c mwifex: free rx_cmd skb in suspended state

-- 
https://patchwork.kernel.org/patch/10571161/

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