Patch "USB: fix usbmon BUG trigger" has been added to the 4.14-stable tree

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

USB: fix usbmon BUG trigger

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
usb-fix-usbmon-bug-trigger.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Pete Zaitcev <[email protected]>
Date: Mon, 8 Jan 2018 15:46:41 -0600
Subject: USB: fix usbmon BUG trigger

From: Pete Zaitcev <[email protected]>

commit 46eb14a6e1585d99c1b9f58d0e7389082a5f466b upstream.

Automated tests triggered this by opening usbmon and accessing the mmap while simultaneously resizing the buffers. This bug was with us since 2006, because typically applications only size the buffers once and thus avoid racing. Reported by Kirill A. Shutemov.

---
 drivers/usb/mon/mon_bin.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

@@ -1004,7 +1004,9 @@ static long mon_bin_ioctl(struct file *f
 		break;
 
 	case MON_IOCQ_RING_SIZE:
+		mutex_lock(&rp->fetch_lock);
 		ret = rp->b_size;
+		mutex_unlock(&rp->fetch_lock);
 		break;
 
 	case MON_IOCT_RING_SIZE:

@@ -1231,12 +1233,16 @@ static int mon_bin_vma_fault(struct vm_f
 	unsigned long offset, chunk_idx;
 	struct page *pageptr;
 
+	mutex_lock(&rp->fetch_lock);
 	offset = vmf->pgoff << PAGE_SHIFT;
-	if (offset >= rp->b_size)
+	if (offset >= rp->b_size) {
+		mutex_unlock(&rp->fetch_lock);
 		return VM_FAULT_SIGBUS;
+	}
 	chunk_idx = offset / CHUNK_SIZE;
 	pageptr = rp->b_vec[chunk_idx].pg;
 	get_page(pageptr);
+	mutex_unlock(&rp->fetch_lock);
 	vmf->page = pageptr;
 	return 0;
 }

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/usb-fix-usbmon-bug-trigger.patch