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authorNeilBrown <neilb@suse.de>2013-07-24 15:37:42 +1000
committerNeilBrown <neilb@suse.de>2013-07-25 16:46:53 +1000
commit0eb25bb027a100f5a9df8991f2f628e7d851bc1e (patch)
tree3e00b7a00db585cf166899506d5fda04ab06a17e
parent30bc9b53878a9921b02e3b5bc4283ac1c6de102a (diff)
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 (24afd80d99) 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>
-rw-r--r--drivers/md/raid10.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 957a719e8c2f..df7b0a06b0ea 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -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));