Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932272AbcDZXnO (ORCPT ); Tue, 26 Apr 2016 19:43:14 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:40945 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754877AbcDZX03 (ORCPT ); Tue, 26 Apr 2016 19:26:29 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Jens Axboe" , "Johannes Thumshirn" , "Hannes Reinecke" Date: Wed, 27 Apr 2016 01:02:24 +0200 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 099/115] bio: return EINTR if copying to user space got interrupted In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8426:ae4:c500:9cba:69ae:962d:6167 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2080 Lines: 57 3.2.80-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Hannes Reinecke commit 2d99b55d378c996b9692a0c93dd25f4ed5d58934 upstream. Commit 35dc248383bbab0a7203fca4d722875bc81ef091 introduced a check for current->mm to see if we have a user space context and only copies data if we do. Now if an IO gets interrupted by a signal data isn't copied into user space any more (as we don't have a user space context) but user space isn't notified about it. This patch modifies the behaviour to return -EINTR from bio_uncopy_user() to notify userland that a signal has interrupted the syscall, otherwise it could lead to a situation where the caller may get a buffer with no data returned. This can be reproduced by issuing SG_IO ioctl()s in one thread while constantly sending signals to it. Fixes: 35dc248 [SCSI] sg: Fix user memory corruption when SG_IO is interrupted by a signal Signed-off-by: Johannes Thumshirn Signed-off-by: Hannes Reinecke Signed-off-by: Jens Axboe [bwh: Backported to 3.2: - Adjust filename - Put the assignment in the existing 'else' block] Signed-off-by: Ben Hutchings --- --- a/fs/bio.c +++ b/fs/bio.c @@ -793,15 +793,19 @@ int bio_uncopy_user(struct bio *bio) if (!bio_flagged(bio, BIO_NULL_MAPPED)) { /* * if we're in a workqueue, the request is orphaned, so - * don't copy into a random user address space, just free. + * don't copy into a random user address space, just free + * and return -EINTR so user space doesn't expect any data. */ if (current->mm) ret = __bio_copy_iov(bio, bmd->iovecs, bmd->sgvecs, bmd->nr_sgvecs, bio_data_dir(bio) == READ, 0, bmd->is_our_pages); - else if (bmd->is_our_pages) - bio_for_each_segment_all(bvec, bio, i) - __free_page(bvec->bv_page); + else { + ret = -EINTR; + if (bmd->is_our_pages) + bio_for_each_segment_all(bvec, bio, i) + __free_page(bvec->bv_page); + } } bio_free_map_data(bmd); bio_put(bio);