Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758805AbcCVLXL (ORCPT ); Tue, 22 Mar 2016 07:23:11 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:56390 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758646AbcCVKlj (ORCPT ); Tue, 22 Mar 2016 06:41:39 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Johannes Thumshirn , Hannes Reinecke , Jens Axboe , Luis Henriques Subject: [PATCH 3.16.y-ckt 013/142] bio: return EINTR if copying to user space got interrupted Date: Tue, 22 Mar 2016 10:39:02 +0000 Message-Id: <1458643271-4227-14-git-send-email-luis.henriques@canonical.com> In-Reply-To: <1458643271-4227-1-git-send-email-luis.henriques@canonical.com> References: <1458643271-4227-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1933 Lines: 52 3.16.7-ckt26 -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. 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 [ luis: backported to 3.16: based on Johannes' backport to 3.14 ] Signed-off-by: Luis Henriques --- block/bio.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/block/bio.c b/block/bio.c index 6467e6afdcd9..529e4195724e 100644 --- a/block/bio.c +++ b/block/bio.c @@ -1110,9 +1110,12 @@ int bio_uncopy_user(struct bio *bio) ret = __bio_copy_iov(bio, 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); + } } kfree(bmd); bio_put(bio);