linux-kernel - [PATCH] wifi: plfxlc: fix potential NULL pointer dereference in plfxlc_usb_wreq

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Date:   Fri,  3 Feb 2023 12:16:44 +0800
From:   Zheng Wang <zyytlz.wz@....com>
To:     srini.raju@...elifi.com
Cc:     kvalo@...nel.org, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Zheng Wang <zyytlz.wz@....com>
Subject: [PATCH] wifi: plfxlc: fix potential NULL pointer dereference in plfxlc_usb_wreq_async()

Although the usb_alloc_urb uses GFP_ATOMIC, tring to make sure the memory
 allocated not to be NULL. But in some low-memory situation, it's still
 possible to return NULL. It'll pass urb as argument in
 usb_fill_bulk_urb, which will finally lead to a NULL pointer dereference.

Fix it by adding additional check.

Note that, as a bug found by static analysis, it can be a false
positive or hard to trigger.

Fixes: 68d57a07bfe5 ("wireless: add plfxlc driver for pureLiFi X, XL, XC devices")

Signed-off-by: Zheng Wang <zyytlz.wz@....com>
---
 drivers/net/wireless/purelifi/plfxlc/usb.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/wireless/purelifi/plfxlc/usb.c b/drivers/net/wireless/purelifi/plfxlc/usb.c
index 76d0a778636a..ac149aa64908 100644
--- a/drivers/net/wireless/purelifi/plfxlc/usb.c
+++ b/drivers/net/wireless/purelifi/plfxlc/usb.c
@@ -496,10 +496,17 @@ int plfxlc_usb_wreq_async(struct plfxlc_usb *usb, const u8 *buffer,
 	struct urb *urb = usb_alloc_urb(0, GFP_ATOMIC);
 	int r;
 
+	if (!urb) {
+		r = -ENOMEM;
+		kfree(urb);
+		goto out;
+	}
 	usb_fill_bulk_urb(urb, udev, usb_sndbulkpipe(udev, EP_DATA_OUT),
 			  (void *)buffer, buffer_len, complete_fn, context);
 
 	r = usb_submit_urb(urb, GFP_ATOMIC);
+
+out:
 	if (r)
 		dev_err(&udev->dev, "Async write submit failed (%d)\n", r);
 
-- 
2.25.1