From: Pete Zaitcev zaitcev@redhat.com
This patch has been added to the 4.1 stable tree. If you have any objections, please let us know.
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[ Upstream commit 46eb14a6e1585d99c1b9f58d0e7389082a5f466b ]
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 Cc: stable stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- 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 9a62e89d6dc0..bbec84dd34fb 100644 --- a/drivers/usb/mon/mon_bin.c +++ b/drivers/usb/mon/mon_bin.c @@ -1000,7 +1000,9 @@ 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: @@ -1227,12 +1229,16 @@ 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; }