Commit 7b1db06f authored by Hannes Reinecke's avatar Hannes Reinecke Committed by Jiri Slaby

bio: return EINTR if copying to user space got interrupted

commit 2d99b55d upstream.

Commit 35dc2483 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.

[js] backport to 3.12

Fixes: 35dc2483 [SCSI] sg: Fix user memory corruption when SG_IO is interrupted by a signal
Signed-off-by: default avatarJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: default avatarHannes Reinecke <hare@suse.de>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
parent 1e719417
...@@ -1051,15 +1051,19 @@ int bio_uncopy_user(struct bio *bio) ...@@ -1051,15 +1051,19 @@ int bio_uncopy_user(struct bio *bio)
if (!bio_flagged(bio, BIO_NULL_MAPPED)) { if (!bio_flagged(bio, BIO_NULL_MAPPED)) {
/* /*
* if we're in a workqueue, the request is orphaned, so * 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) if (current->mm)
ret = __bio_copy_iov(bio, bmd->iovecs, bmd->sgvecs, ret = __bio_copy_iov(bio, bmd->iovecs, bmd->sgvecs,
bmd->nr_sgvecs, bio_data_dir(bio) == READ, bmd->nr_sgvecs, bio_data_dir(bio) == READ,
0, bmd->is_our_pages); 0, bmd->is_our_pages);
else if (bmd->is_our_pages) else {
bio_for_each_segment_all(bvec, bio, i) ret = -EINTR;
__free_page(bvec->bv_page); if (bmd->is_our_pages)
bio_for_each_segment_all(bvec, bio, i)
__free_page(bvec->bv_page);
}
} }
bio_free_map_data(bmd); bio_free_map_data(bmd);
bio_put(bio); bio_put(bio);
......
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