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[18.9.28.11]) by mx.google.com with ESMTPS id g187si92161qkc.5.2019.06.09.18.51.47 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 09 Jun 2019 18:51:47 -0700 (PDT) Received-SPF: pass (google.com: domain of tytso@mit.edu designates 18.9.28.11 as permitted sender) client-ip=18.9.28.11; Authentication-Results: mx.google.com; spf=pass (google.com: domain of tytso@mit.edu designates 18.9.28.11 as permitted sender) smtp.mailfrom=tytso@mit.edu Received: from callcc.thunk.org ([66.31.38.53]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id x5A1pjIR002876 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Sun, 9 Jun 2019 21:51:46 -0400 Received: by callcc.thunk.org (Postfix, from userid 15806) id C99A2420481; Sun, 9 Jun 2019 21:51:45 -0400 (EDT) Date: Sun, 9 Jun 2019 21:51:45 -0400 From: "Theodore Ts'o" To: "Darrick J. Wong" Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 1/8] mm/fs: don't allow writes to immutable files Message-ID: <20190610015145.GB3266@mit.edu> References: <155552786671.20411.6442426840435740050.stgit@magnolia> <155552787330.20411.11893581890744963309.stgit@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <155552787330.20411.11893581890744963309.stgit@magnolia> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Apr 17, 2019 at 12:04:33PM -0700, Darrick J. Wong wrote: > diff --git a/mm/memory.c b/mm/memory.c > index ab650c21bccd..dfd5eba278d6 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -2149,6 +2149,9 @@ static vm_fault_t do_page_mkwrite(struct vm_fault *vmf) > > vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; > > + if (vmf->vma->vm_file && IS_IMMUTABLE(file_inode(vmf->vma->vm_file))) > + return VM_FAULT_SIGBUS; > + > ret = vmf->vma->vm_ops->page_mkwrite(vmf); > /* Restore original flags so that caller is not surprised */ > vmf->flags = old_flags; Shouldn't this check be moved before the modification of vmf->flags? It looks like do_page_mkwrite() isn't supposed to be returning with vmf->flags modified, lest "the caller gets surprised". - Ted