From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f198.google.com (mail-qk0-f198.google.com [209.85.220.198]) by kanga.kvack.org (Postfix) with ESMTP id AEB546B0253 for ; Wed, 18 Oct 2017 15:10:45 -0400 (EDT) Received: by mail-qk0-f198.google.com with SMTP id k123so7014041qke.10 for ; Wed, 18 Oct 2017 12:10:45 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id v21si166007qth.49.2017.10.18.12.10.44 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 18 Oct 2017 12:10:44 -0700 (PDT) Date: Wed, 18 Oct 2017 21:10:39 +0200 From: Andrea Arcangeli Subject: Re: [PATCH 1/1] userfaultfd: hugetlbfs: prevent UFFDIO_COPY to fill beyond the end of i_size Message-ID: <20171018191039.GL17239@redhat.com> References: <20171016223914.2421-1-aarcange@redhat.com> <20171016223914.2421-2-aarcange@redhat.com> <20171016161443.5365a280c44dc80e8c11298c@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171016161443.5365a280c44dc80e8c11298c@linux-foundation.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: linux-mm@kvack.org, Mike Rapoport , "Dr. David Alan Gilbert" , Mike Kravetz On Mon, Oct 16, 2017 at 04:14:43PM -0700, Andrew Morton wrote: > On Tue, 17 Oct 2017 00:39:14 +0200 Andrea Arcangeli wrote: > > > kernel BUG at fs/hugetlbfs/inode.c:484! > > RIP: 0010:[] [] remove_inode_hugepages+0x3d0/0x410 > > Call Trace: > > [] hugetlbfs_setattr+0xd9/0x130 > > [] notify_change+0x292/0x410 > > [] ? security_inode_need_killpriv+0x16/0x20 > > [] do_truncate+0x65/0xa0 > > [] ? do_sys_ftruncate.constprop.3+0xe5/0x180 > > [] do_sys_ftruncate.constprop.3+0x11a/0x180 > > [] SyS_ftruncate+0xe/0x10 > > [] tracesys+0xd9/0xde > > > > This oops was caused by the lack of i_size check in > > hugetlb_mcopy_atomic_pte. mmap() can still succeed beyond the end of > > the i_size after vmtruncate zapped vmas in those ranges, but the > > faults must not succeed, and that includes UFFDIO_COPY. > > > > We could differentiate the retval to userland to represent a SIGBUS > > like a page fault would do (vs SIGSEGV), but it doesn't seem very > > useful and we'd need to pick a random retval as there's no meaningful > > syscall retval that would differentiate from SIGSEGV and SIGBUS, > > there's just -EFAULT. > > > > Reviewed-by: Mike Kravetz > > Signed-off-by: Andrea Arcangeli > > No cc:stable? The patch applies to 4.13 textually... Yes, I should have CC'ed stable. Last time I CC'ed stable I didn't submit it in the right way, I should have added cc:stable to the commit body, this time. I can resend with cc:stable if you prefer. Thanks! Andrea -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org