From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:52983 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750890AbcBLIjT (ORCPT ); Fri, 12 Feb 2016 03:39:19 -0500 From: Hannes Reinecke To: "Martin K. Petersen" Cc: James Bottomley , Doug Gilbert , linux-scsi@vger.kernel.org, Ewan Milne , Jens Axboe , linux-block@vger.kernel.org, Hannes Reinecke , Johannes Thumshirn , stable@vger.kernel.org, #@suse.de, v.3.11+@suse.de Subject: [PATCH] bio: return EINTR if copying to user space got interrupted Date: Fri, 12 Feb 2016 09:39:15 +0100 Message-Id: <1455266355-44676-1-git-send-email-hare@suse.de> Sender: stable-owner@vger.kernel.org List-ID: 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 Cc: stable@vger.kernel.org # v.3.11+ --- block/bio.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/block/bio.c b/block/bio.c index dbabd48..24e5b69 100644 --- a/block/bio.c +++ b/block/bio.c @@ -1090,9 +1090,12 @@ 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 && bio_data_dir(bio) == READ) + if (!current->mm) + ret = -EINTR; + else if (bio_data_dir(bio) == READ) ret = bio_copy_to_iter(bio, bmd->iter); if (bmd->is_our_pages) bio_free_pages(bio); -- 1.8.5.6