From a3f8f7dc7ad652cd84c12cb5efa0f7722dff4786 Mon Sep 17 00:00:00 2001 From: Lars Ellenberg Date: Wed, 27 Mar 2013 14:08:43 +0100 Subject: [PATCH] drbd: validate resync_after dependency on attach already We validated resync_after dependencies, if changed via disk-options. But we did not validate them when first created via attach. We also did not check or cleanup dependencies that used to be correct, but now point to meanwhile removed minor devices. If the drbd_resync_after_valid() validation in disk-options tried to follow a dependency chain in this way, this could lead to NULL pointer dereference. Validate resync_after settings in drbd_adm_attach() already, as well as in drbd_adm_disk_opts(), and and only reject dependency loops. Depending on non-existing disks is allowed and equivalent to no dependency. Signed-off-by: Philipp Reisner Signed-off-by: Lars Ellenberg Signed-off-by: Jens Axboe --- drivers/block/drbd/drbd_nl.c | 6 ++++++ drivers/block/drbd/drbd_worker.c | 15 ++++++++++++--- 2 files changed, 18 insertions(+), 3 deletions(-) diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c index 39e9a91a8f31..9e3f441e7e84 100644 --- a/drivers/block/drbd/drbd_nl.c +++ b/drivers/block/drbd/drbd_nl.c @@ -1381,6 +1381,12 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info) goto fail; } + write_lock_irq(&global_state_lock); + retcode = drbd_resync_after_valid(mdev, new_disk_conf->resync_after); + write_unlock_irq(&global_state_lock); + if (retcode != NO_ERROR) + goto fail; + rcu_read_lock(); nc = rcu_dereference(mdev->tconn->net_conf); if (nc) { diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c index 7f51f88b0a80..891c0ecaa292 100644 --- a/drivers/block/drbd/drbd_worker.c +++ b/drivers/block/drbd/drbd_worker.c @@ -1426,7 +1426,7 @@ static int _drbd_may_sync_now(struct drbd_conf *mdev) int resync_after; while (1) { - if (!odev->ldev) + if (!odev->ldev || odev->state.disk == D_DISKLESS) return 1; rcu_read_lock(); resync_after = rcu_dereference(odev->ldev->disk_conf)->resync_after; @@ -1434,7 +1434,7 @@ static int _drbd_may_sync_now(struct drbd_conf *mdev) if (resync_after == -1) return 1; odev = minor_to_mdev(resync_after); - if (!expect(odev)) + if (!odev) return 1; if ((odev->state.conn >= C_SYNC_SOURCE && odev->state.conn <= C_PAUSED_SYNC_T) || @@ -1516,7 +1516,7 @@ enum drbd_ret_code drbd_resync_after_valid(struct drbd_conf *mdev, int o_minor) if (o_minor == -1) return NO_ERROR; - if (o_minor < -1 || minor_to_mdev(o_minor) == NULL) + if (o_minor < -1 || o_minor > MINORMASK) return ERR_RESYNC_AFTER; /* check for loops */ @@ -1525,6 +1525,15 @@ enum drbd_ret_code drbd_resync_after_valid(struct drbd_conf *mdev, int o_minor) if (odev == mdev) return ERR_RESYNC_AFTER_CYCLE; + /* You are free to depend on diskless, non-existing, + * or not yet/no longer existing minors. + * We only reject dependency loops. + * We cannot follow the dependency chain beyond a detached or + * missing minor. + */ + if (!odev || !odev->ldev || odev->state.disk == D_DISKLESS) + return NO_ERROR; + rcu_read_lock(); resync_after = rcu_dereference(odev->ldev->disk_conf)->resync_after; rcu_read_unlock(); -- 2.11.0