patch "usb: gadget: f_hid: fixed NULL pointer dereference" added to usb-linus

PATCH [email protected] 1 participant 1 message Jul 27, 2021

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2021-07-27 13:56 UTC #0 lore raw

This is a note to let you know that I've just added the patch titled

usb: gadget: f_hid: fixed NULL pointer dereference

to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From 2867652e4766360adf14dfda3832455e04964f2a Mon Sep 17 00:00:00 2001
From: Phil Elwell <[email protected]>
Date: Fri, 23 Jul 2021 18:59:30 +0300
Subject: usb: gadget: f_hid: fixed NULL pointer dereference

Disconnecting and reconnecting the USB cable can lead to crashes and a variety of kernel log spam.

The problem was found and reproduced on the Raspberry Pi [1] and the original fix was created in Raspberry's own fork [2].

Link https://github.com/raspberrypi/linux/issues/3870 [1]

Link https://github.com/raspberrypi/linux/commit/a6e47d5f4efbd2ea6a0b6565cd2f9b7bb217ded5 [2]

Signed-off-by Maxim Devaev <[email protected]>

Signed-off-by Phil Elwell <[email protected]>

Cc stable <[email protected]>

Link https://lore.kernel.org/r/[email protected] open here

Signed-off-by Greg Kroah-Hartman <[email protected]>

---
 drivers/usb/gadget/function/f_hid.c | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

drivers/usb/gadget/function/f_hid.c +20 -6

index 02683ac0719d..08e73e8127b1 100644
@@ -338,6 +338,11 @@ static ssize_t f_hidg_write(struct file *file, const char __user *buffer,
 
 	spin_lock_irqsave(&hidg->write_spinlock, flags);
 
+	if (!hidg->req) {
+		spin_unlock_irqrestore(&hidg->write_spinlock, flags);
+		return -ESHUTDOWN;
+	}
+
 #define WRITE_COND (!hidg->write_pending)
 try_again:
 	/* write queue */

@@ -358,8 +363,14 @@ static ssize_t f_hidg_write(struct file *file, const char __user *buffer,
 	count  = min_t(unsigned, count, hidg->report_length);
 
 	spin_unlock_irqrestore(&hidg->write_spinlock, flags);
-	status = copy_from_user(req->buf, buffer, count);
 
+	if (!req) {
+		ERROR(hidg->func.config->cdev, "hidg->req is NULL\n");
+		status = -ESHUTDOWN;
+		goto release_write_pending;
+	}
+
+	status = copy_from_user(req->buf, buffer, count);
 	if (status != 0) {
 		ERROR(hidg->func.config->cdev,
 			"copy_from_user error\n");

@@ -387,14 +398,17 @@ static ssize_t f_hidg_write(struct file *file, const char __user *buffer,
 
 	spin_unlock_irqrestore(&hidg->write_spinlock, flags);
 
+	if (!hidg->in_ep->enabled) {
+		ERROR(hidg->func.config->cdev, "in_ep is disabled\n");
+		status = -ESHUTDOWN;
+		goto release_write_pending;
+	}
+
 	status = usb_ep_queue(hidg->in_ep, req, GFP_ATOMIC);
-	if (status < 0) {
-		ERROR(hidg->func.config->cdev,
-			"usb_ep_queue error on int endpoint %zd\n", status);
+	if (status < 0)
 		goto release_write_pending;
-	} else {
+	else
 		status = count;
-	}
 
 	return status;
 release_write_pending:

Signature · 1 line

2.32.0