Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965277AbcCIXfP (ORCPT ); Wed, 9 Mar 2016 18:35:15 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:41015 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964933AbcCIXRu (ORCPT ); Wed, 9 Mar 2016 18:17:50 -0500 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Johannes Thumshirn , Hannes Reinecke , Jens Axboe , Jiri Slaby , Kamal Mostafa Subject: [PATCH 3.13.y-ckt 086/138] bio: return EINTR if copying to user space got interrupted Date: Wed, 9 Mar 2016 15:13:33 -0800 Message-Id: <1457565265-15195-87-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 2.7.0 In-Reply-To: <1457565265-15195-1-git-send-email-kamal@canonical.com> References: <1457565265-15195-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2261 Lines: 64 3.13.11-ckt36 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ 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. [js] backport to 3.12 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 Signed-off-by: Jiri Slaby Signed-off-by: Kamal Mostafa --- fs/bio.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/fs/bio.c b/fs/bio.c index 33d79a4..99367f4 100644 --- a/fs/bio.c +++ b/fs/bio.c @@ -1051,15 +1051,19 @@ 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); -- 2.7.0