Patch "USB: fix usbmon BUG trigger" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

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

    USB: fix usbmon BUG trigger

to the 4.9-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-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 46eb14a6e1585d99c1b9f58d0e7389082a5f466b Mon Sep 17 00:00:00 2001
From: Pete Zaitcev <zaitcev@redhat.com>
Date: Mon, 8 Jan 2018 15:46:41 -0600
Subject: USB: fix usbmon BUG trigger

From: Pete Zaitcev <zaitcev@redhat.com>

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.

Reported-by: <syzbot+f9831b881b3e849829fc@syzkaller.appspotmail.com>
Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/drivers/usb/mon/mon_bin.c
+++ b/drivers/usb/mon/mon_bin.c
@@ -1002,7 +1002,9 @@ 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:
@@ -1229,12 +1231,16 @@ static int mon_bin_vma_fault(struct vm_a
 	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 zaitcev@redhat.com are

queue-4.9/usb-fix-usbmon-bug-trigger.patch