From 079fa166a2874985ae58b2e21e26e1cbc91127d4 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Sat, 10 Sep 2011 17:21:23 +1000 Subject: [PATCH] md/raid1,10: Remove use-after-free bug in make_request. A single request to RAID1 or RAID10 might result in multiple requests if there are known bad blocks that need to be avoided. To detect if we need to submit another write request we test: if (sectors_handled < (bio->bi_size >> 9)) { However this is after we call **_write_done() so the 'bio' no longer belongs to us - the writes could have completed and the bio freed. So move the **_write_done call until after the test against bio->bi_size. This addresses https://bugzilla.kernel.org/show_bug.cgi?id=41862 Reported-by: Bruno Wolff III Tested-by: Bruno Wolff III Signed-off-by: NeilBrown --- drivers/md/raid1.c | 14 +++++++++----- drivers/md/raid10.c | 13 ++++++++----- 2 files changed, 17 insertions(+), 10 deletions(-) diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index 32323f0afd89..f4622dd8fc59 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -1099,12 +1099,11 @@ read_again: bio_list_add(&conf->pending_bio_list, mbio); spin_unlock_irqrestore(&conf->device_lock, flags); } - r1_bio_write_done(r1_bio); - - /* In case raid1d snuck in to freeze_array */ - wake_up(&conf->wait_barrier); - + /* Mustn't call r1_bio_write_done before this next test, + * as it could result in the bio being freed. + */ if (sectors_handled < (bio->bi_size >> 9)) { + r1_bio_write_done(r1_bio); /* We need another r1_bio. It has already been counted * in bio->bi_phys_segments */ @@ -1117,6 +1116,11 @@ read_again: goto retry_write; } + r1_bio_write_done(r1_bio); + + /* In case raid1d snuck in to freeze_array */ + wake_up(&conf->wait_barrier); + if (do_sync || !bitmap || !plugged) md_wakeup_thread(mddev->thread); diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index f6873fc8e5ee..d7a8468ddeab 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -1132,13 +1132,12 @@ retry_write: spin_unlock_irqrestore(&conf->device_lock, flags); } - /* Remove the bias on 'remaining' */ - one_write_done(r10_bio); - - /* In case raid10d snuck in to freeze_array */ - wake_up(&conf->wait_barrier); + /* Don't remove the bias on 'remaining' (one_write_done) until + * after checking if we need to go around again. + */ if (sectors_handled < (bio->bi_size >> 9)) { + one_write_done(r10_bio); /* We need another r10_bio. It has already been counted * in bio->bi_phys_segments. */ @@ -1152,6 +1151,10 @@ retry_write: r10_bio->state = 0; goto retry_write; } + one_write_done(r10_bio); + + /* In case raid10d snuck in to freeze_array */ + wake_up(&conf->wait_barrier); if (do_sync || !mddev->bitmap || !plugged) md_wakeup_thread(mddev->thread); -- 2.20.1