From: Hannes Reinecke Date: Fri, 12 Feb 2016 08:39:15 +0000 (+0100) Subject: bio: return EINTR if copying to user space got interrupted X-Git-Tag: v3.16.35~364 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=04e0f4eebfe7419444dd5dd7ea476a7b25030054;p=thirdparty%2Fkernel%2Fstable.git bio: return EINTR if copying to user space got interrupted 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 Signed-off-by: Hannes Reinecke Signed-off-by: Jens Axboe [ luis: backported to 3.16: based on Johannes' backport to 3.14 ] Signed-off-by: Luis Henriques --- diff --git a/block/bio.c b/block/bio.c index 6467e6afdcd98..529e4195724e3 100644 --- a/block/bio.c +++ b/block/bio.c @@ -1110,9 +1110,12 @@ 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);