md/raid10: remove use-after-free bug. (0eb25bb0) · Commits · 戴 / test

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 () and can cause an oops, so fix is suitable for any -stable since then. Cc: stable@vger.kernel.org (3.3+) Signed-off-by:

NeilBrown <neilb@suse.de>

drivers/md/raid10.c

+7 −1

Original line number	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;
		wbio = r10_bio->devs[1].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) {
		atomic_inc(&conf->mirrors[d].rdev->nr_pending);
		md_sync_acct(conf->mirrors[d].rdev->bdev, bio_sectors(wbio));
		generic_make_request(wbio);
		}
		if (wbio2 && wbio2->bi_end_io) {
		if (wbio2) {
		atomic_inc(&conf->mirrors[d].replacement->nr_pending);
		md_sync_acct(conf->mirrors[d].replacement->bdev,
		bio_sectors(wbio2));

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