This is a note to let you know that I've just added the patch titled
bio: return EINTR if copying to user space got interrupted
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:
bio-return-eintr-if-copying-to-user-space-got-interrupted.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 <stable@xxxxxxxxxxxxxxx> know about it.
>From 2d99b55d378c996b9692a0c93dd25f4ed5d58934 Mon Sep 17 00:00:00 2001
From: Hannes Reinecke <hare@xxxxxxx>
Date: Fri, 12 Feb 2016 09:39:15 +0100
Subject: bio: return EINTR if copying to user space got interrupted
From: Hannes Reinecke <hare@xxxxxxx>
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 <jthumshirn@xxxxxxx>
Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
block/bio.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
--- 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);
Patches currently in stable-queue which might be from hare@xxxxxxx are
queue-4.4/target-fix-remote-port-tmr-abort-se_cmd-fabric-stop.patch
queue-4.4/target-fix-lun_reset-active-tmr-descriptor-handling.patch
queue-4.4/target-fix-race-with-scf_send_delayed_tas-handling.patch
queue-4.4/bio-return-eintr-if-copying-to-user-space-got-interrupted.patch
queue-4.4/target-fix-lun_reset-active-i-o-handling-for-ack_kref.patch
queue-4.4/target-fix-tas-handling-for-multi-session-se_node_acls.patch
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