| From 0eb25bb027a100f5a9df8991f2f628e7d851bc1e Mon Sep 17 00:00:00 2001 |
| From: NeilBrown <neilb@suse.de> |
| Date: Wed, 24 Jul 2013 15:37:42 +1000 |
| Subject: md/raid10: remove use-after-free bug. |
| |
| From: NeilBrown <neilb@suse.de> |
| |
| commit 0eb25bb027a100f5a9df8991f2f628e7d851bc1e upstream. |
| |
| 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 (24afd80d99) and can cause an |
| oops, so fix is suitable for any -stable since then. |
| |
| Signed-off-by: NeilBrown <neilb@suse.de> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/md/raid10.c | 8 +++++++- |
| 1 file changed, 7 insertions(+), 1 deletion(-) |
| |
| --- a/drivers/md/raid10.c |
| +++ b/drivers/md/raid10.c |
| @@ -2268,12 +2268,18 @@ static void recovery_request_write(struc |
| 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)); |
