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Commit 0eb25bb0 authored by NeilBrown's avatar NeilBrown
Browse files

md/raid10: remove use-after-free bug. 



We always need to be careful when calling generic_make_request, as it
can start a chain of events which might free something that we are
using.

Here is one place I wasn't careful enough.  If the wbio2 is not in
use, then it might get freed at the first generic_make_request call.
So perform all necessary tests first.

This bug was introduced in 3.3-rc3 (24afd80d) and can cause an
oops, so fix is suitable for any -stable since then.

Cc: stable@vger.kernel.org (3.3+)
Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent 30bc9b53

drivers/md/raid10.c

+7 −1
Original line number Original line Diff line number Diff line
@@ -2290,12 +2290,18 @@ static void recovery_request_write(struct mddev *mddev, struct r10bio *r10_bio) 
	d = r10_bio->devs[1].devnum;

	d = r10_bio->devs[1].devnum;

	wbio = r10_bio->devs[1].bio;

	wbio = r10_bio->devs[1].bio;

	wbio2 = r10_bio->devs[1].repl_bio;

	wbio2 = r10_bio->devs[1].repl_bio;

	/* Need to test wbio2->bi_end_io before we call

	 * generic_make_request as if the former is NULL,

	 * the latter is free to free wbio2.

	 */

	if (wbio2 && !wbio2->bi_end_io)

		wbio2 = NULL;

	if (wbio->bi_end_io) {

	if (wbio->bi_end_io) {

		atomic_inc(&conf->mirrors[d].rdev->nr_pending);

		atomic_inc(&conf->mirrors[d].rdev->nr_pending);

		md_sync_acct(conf->mirrors[d].rdev->bdev, bio_sectors(wbio));

		md_sync_acct(conf->mirrors[d].rdev->bdev, bio_sectors(wbio));

		generic_make_request(wbio);

		generic_make_request(wbio);

	}

	}

	if (wbio2 && wbio2->bi_end_io) {

	if (wbio2) {

		atomic_inc(&conf->mirrors[d].replacement->nr_pending);

		atomic_inc(&conf->mirrors[d].replacement->nr_pending);

		md_sync_acct(conf->mirrors[d].replacement->bdev,

		md_sync_acct(conf->mirrors[d].replacement->bdev,

			     bio_sectors(wbio2));

			     bio_sectors(wbio2));