linux-kernel - [PATCH 4.4 75/87] USB: fix usbmon BUG trigger

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20180115123357.778782614@linuxfoundation.org>
Date:   Mon, 15 Jan 2018 13:35:14 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        syzbot+f9831b881b3e849829fc@...kaller.appspotmail.com,
        Pete Zaitcev <zaitcev@...hat.com>
Subject: [PATCH 4.4 75/87] USB: fix usbmon BUG trigger

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Pete Zaitcev <zaitcev@...hat.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@...kaller.appspotmail.com>
Signed-off-by: Pete Zaitcev <zaitcev@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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
@@ -1001,7 +1001,9 @@ 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:
@@ -1228,12 +1230,16 @@ 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;
 }