From 435db24bb91f7dd16940d8ddedc3b5ca75547fb5 Mon Sep 17 00:00:00 2001 From: Pete Zaitcev Date: Mon, 8 Jan 2018 15:46:41 -0600 Subject: [PATCH] USB: fix usbmon BUG trigger 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: Signed-off-by: Pete Zaitcev Signed-off-by: Greg Kroah-Hartman --- drivers/usb/mon/mon_bin.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/usb/mon/mon_bin.c b/drivers/usb/mon/mon_bin.c index 1a874a1f3890eb..80b37d214bebf0 100644 --- 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 *file, unsigned int cmd, unsigned long arg 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_area_struct *vma, struct vm_fault *vmf) 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; }