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
Cc: stable@xxxxxxxxxxxxxxx #v3.14
Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
Signed-off-by: Johannes Thumshirn <jthumshirn@xxxxxxx>
---
fs/bio.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/fs/bio.c b/fs/bio.c
index b2b1451..6d8cf43 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -1096,9 +1096,12 @@ 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);
--
2.7.2
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