Messages in this thread Patch in this message | | | From | Kamal Mostafa <> | Subject | [PATCH 3.19.y-ckt 106/196] bio: return EINTR if copying to user space got interrupted | Date | Tue, 8 Mar 2016 16:29:24 -0800 |
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3.19.8-ckt16 -stable review patch. If anyone has any objections, please let me know.
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From: Hannes Reinecke <hare@suse.de>
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@suse.de> Signed-off-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@fb.com> [ luis: backported to 3.16: based on Johannes' backport to 3.14 ] Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- block/bio.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/block/bio.c b/block/bio.c index dae3483..a2eb041 100644 --- a/block/bio.c +++ b/block/bio.c @@ -1120,9 +1120,12 @@ int bio_uncopy_user(struct bio *bio) ret = __bio_copy_iov(bio, bmd->sgvecs, bmd->nr_sgvecs, bio_data_dir(bio) == READ, 0, bmd->is_our_pages); - else if (bmd->is_our_pages) - bio_for_each_segment_all(bvec, bio, i) - __free_page(bvec->bv_page); + else { + ret = -EINTR; + if (bmd->is_our_pages) + bio_for_each_segment_all(bvec, bio, i) + __free_page(bvec->bv_page); + } } kfree(bmd); bio_put(bio); -- 2.7.0
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