From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:53588 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754328AbdIHHLA (ORCPT ); Fri, 8 Sep 2017 03:11:00 -0400 Subject: Patch "scsi: sg: recheck MMAP_IO request length with lock held" has been added to the 4.4-stable tree To: toddpoynor@google.com, dgilbert@interlog.com, gregkh@linuxfoundation.org, martin.petersen@oracle.com Cc: , From: Date: Fri, 08 Sep 2017 09:10:49 +0200 Message-ID: <150485464916462@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled scsi: sg: recheck MMAP_IO request length with lock held to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: scsi-sg-recheck-mmap_io-request-length-with-lock-held.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 8d26f491116feaa0b16de370b6a7ba40a40fa0b4 Mon Sep 17 00:00:00 2001 From: Todd Poynor Date: Tue, 15 Aug 2017 21:48:43 -0700 Subject: scsi: sg: recheck MMAP_IO request length with lock held From: Todd Poynor commit 8d26f491116feaa0b16de370b6a7ba40a40fa0b4 upstream. Commit 1bc0eb044615 ("scsi: sg: protect accesses to 'reserved' page array") adds needed concurrency protection for the "reserve" buffer. Some checks that are initially made outside the lock are replicated once the lock is taken to ensure the checks and resulting decisions are made using consistent state. The check that a request with flag SG_FLAG_MMAP_IO set fits in the reserve buffer also needs to be performed again under the lock to ensure the reserve buffer length compared against matches the value in effect when the request is linked to the reserve buffer. An -ENOMEM should be returned in this case, instead of switching over to an indirect buffer as for non-MMAP_IO requests. Signed-off-by: Todd Poynor Acked-by: Douglas Gilbert Signed-off-by: Martin K. Petersen Signed-off-by: Greg Kroah-Hartman --- drivers/scsi/sg.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -1757,9 +1757,12 @@ sg_start_req(Sg_request *srp, unsigned c !sfp->res_in_use) { sfp->res_in_use = 1; sg_link_reserve(sfp, srp, dxfer_len); - } else if ((hp->flags & SG_FLAG_MMAP_IO) && sfp->res_in_use) { + } else if (hp->flags & SG_FLAG_MMAP_IO) { + res = -EBUSY; /* sfp->res_in_use == 1 */ + if (dxfer_len > rsv_schp->bufflen) + res = -ENOMEM; mutex_unlock(&sfp->f_mutex); - return -EBUSY; + return res; } else { res = sg_build_indirect(req_schp, sfp, dxfer_len); if (res) { Patches currently in stable-queue which might be from toddpoynor@google.com are queue-4.4/scsi-sg-recheck-mmap_io-request-length-with-lock-held.patch queue-4.4/scsi-sg-protect-against-races-between-mmap-and-sg_set_reserved_size.patch