From 001a88687aff26d62f8b61d55c6973618cf0f72f Mon Sep 17 00:00:00 2001 From: Lars Ellenberg Date: Thu, 8 Mar 2012 16:43:45 +0100 Subject: drbd: fix potential data corruption and protocol error We assumed only bios with bi_idx == 0 would end up in drbd_make_request(). That is wrong. At least device mapper, in __clone_and_map(), may submit clones only covering a partial bio, but sharing the original bvec, by adjusting bi_idx and relevant other bio members of the clone. We used __bio_for_each_segment() in various places, even though that is documented as * drivers should not use the __ version unless they _really_ want to * run through the entire bio and not just pending pieces Impact: we would send the full bio bvec, even for the clone with bi_idx > 0, which will cause data corruption on the peer (because we submit wrong data at the clone offset), and will cause a DRBD protocol error, disconnect/reconnect and resync (thus fixing the corruption), because the next package header would be expected right in the middle of the sent data, causing DRBD magic mismatch. Fix: drop the assert, and use bio_for_each_segment() instead of the __ version. Conflicts: drbd/drbd_tracing.c Signed-off-by: Philipp Reisner Signed-off-by: Lars Ellenberg --- drivers/block/drbd/drbd_main.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/block/drbd/drbd_main.c') diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c index 8ca8925520ad..f6cfc45b862a 100644 --- a/drivers/block/drbd/drbd_main.c +++ b/drivers/block/drbd/drbd_main.c @@ -2734,7 +2734,7 @@ static int _drbd_send_bio(struct drbd_conf *mdev, struct bio *bio) struct bio_vec *bvec; int i; /* hint all but last page with MSG_MORE */ - __bio_for_each_segment(bvec, bio, i, 0) { + bio_for_each_segment(bvec, bio, i) { if (!_drbd_no_send_page(mdev, bvec->bv_page, bvec->bv_offset, bvec->bv_len, i == bio->bi_vcnt -1 ? 0 : MSG_MORE)) @@ -2748,7 +2748,7 @@ static int _drbd_send_zc_bio(struct drbd_conf *mdev, struct bio *bio) struct bio_vec *bvec; int i; /* hint all but last page with MSG_MORE */ - __bio_for_each_segment(bvec, bio, i, 0) { + bio_for_each_segment(bvec, bio, i) { if (!_drbd_send_page(mdev, bvec->bv_page, bvec->bv_offset, bvec->bv_len, i == bio->bi_vcnt -1 ? 0 : MSG_MORE)) -- cgit v1.2.1