On Tue, Feb 28, 2017 at 4:42 PM, Andrea Arcangeli <aarcange@xxxxxxxxxx> wrote: > Hello Dmitry, > > On Tue, Feb 28, 2017 at 03:04:53PM +0100, Dmitry Vyukov wrote: >> Hello, >> >> The following program triggers GPF in __do_fault: >> https://gist.githubusercontent.com/dvyukov/27345737fca18d92ef761e7fa08aec9b/raw/d99d02511d0bf9a8d6f6bd9c79d373a26924e974/gistfile1.txt > > Can you verify this fix: Applied the patch on bots. > From a65381bc86d2963713b6a9c4a73cded7dd184282 Mon Sep 17 00:00:00 2001 > From: Andrea Arcangeli <aarcange@xxxxxxxxxx> > Date: Tue, 28 Feb 2017 16:36:59 +0100 > Subject: [PATCH 1/1] userfaultfd: shmem: __do_fault requires VM_FAULT_NOPAGE > > __do_fault assumes vmf->page has been initialized and is valid if > VM_FAULT_NOPAGE is not returned by vma->vm_ops->fault(vma, vmf). > > handle_userfault() in turn should return VM_FAULT_NOPAGE if it doesn't > return VM_FAULT_SIGBUS or VM_FAULT_RETRY (the other two > possibilities). > > This VM_FAULT_NOPAGE case is only invoked when signal are pending and > it didn't matter for anonymous memory before. It only started to > matter since shmem was introduced. hugetlbfs also takes a different > path and doesn't exercise __do_fault. > > Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx> > --- > fs/userfaultfd.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c > index fb6d02b..de28f43 100644 > --- a/fs/userfaultfd.c > +++ b/fs/userfaultfd.c > @@ -500,7 +500,7 @@ int handle_userfault(struct vm_fault *vmf, unsigned long reason) > * in such case. > */ > down_read(&mm->mmap_sem); > - ret = 0; > + ret = VM_FAULT_NOPAGE; > } > } > > > -- > You received this message because you are subscribed to the Google Groups "syzkaller" group. > To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller+unsubscribe@xxxxxxxxxxxxxxxx. > For more options, visit https://groups.google.com/d/optout. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
