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bio: return EINTR if copying to user space got interrupted 

Commit 35dc248383 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@suse.de>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Cc: stable@vger.kernel.org # v.3.11+
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Hannes Reinecke 2016-02-12 09:39:15 +01:00 committed by Jens Axboe
parent f8e68a7c9a
commit 2d99b55d37
1 changed files with 5 additions and 2 deletions
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7
block/bio.c
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@ -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);