dm persistent data: handle space map checker creation failure

If CONFIG_DM_DEBUG_SPACE_MAPS is enabled and dm_sm_checker_create()
fails, dm_tm_create_internal() would still return success even though it
cleaned up all resources it was supposed to have created.  This will
lead to a kernel crash:

general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC
...
RIP: 0010:[<ffffffff81593659>]  [<ffffffff81593659>] dm_bufio_get_block_size+0x9/0x20
Call Trace:
  [<ffffffff81599bae>] dm_bm_block_size+0xe/0x10
  [<ffffffff8159b8b8>] sm_ll_init+0x78/0xd0
  [<ffffffff8159c1a6>] sm_ll_new_disk+0x16/0xa0
  [<ffffffff8159c98e>] dm_sm_disk_create+0xfe/0x160
  [<ffffffff815abf6e>] dm_pool_metadata_open+0x16e/0x6a0
  [<ffffffff815aa010>] pool_ctr+0x3f0/0x900
  [<ffffffff8158d565>] dm_table_add_target+0x195/0x450
  [<ffffffff815904c4>] table_load+0xe4/0x330
  [<ffffffff815917ea>] ctl_ioctl+0x15a/0x2c0
  [<ffffffff81591963>] dm_ctl_ioctl+0x13/0x20
  [<ffffffff8116a4f8>] do_vfs_ioctl+0x98/0x560
  [<ffffffff8116aa51>] sys_ioctl+0x91/0xa0
  [<ffffffff81869f52>] system_call_fastpath+0x16/0x1b

Fix the space map checker code to return an appropriate ERR_PTR and have
dm_sm_disk_create() and dm_tm_create_internal() check for it with
IS_ERR.

Reported-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

diff --git a/drivers/md/persistent-data/dm-space-map-checker.c b/drivers/md/persistent-data/dm-space-map-checker.c
index 50ed53b..6d7c832 100644 (file)
--- a/drivers/md/persistent-data/dm-space-map-checker.c
+++ b/drivers/md/persistent-data/dm-space-map-checker.c
@@ -343,25 +343,25 @@ struct dm_space_map *dm_sm_checker_create(struct dm_space_map *sm)
        int r;
        struct sm_checker *smc;
 
-       if (!sm)
-               return NULL;
+       if (IS_ERR_OR_NULL(sm))
+               return ERR_PTR(-EINVAL);
 
        smc = kmalloc(sizeof(*smc), GFP_KERNEL);
        if (!smc)
-               return NULL;
+               return ERR_PTR(-ENOMEM);
 
        memcpy(&smc->sm, &ops_, sizeof(smc->sm));
        r = ca_create(&smc->old_counts, sm);
        if (r) {
                kfree(smc);
-               return NULL;
+               return ERR_PTR(r);
        }
 
        r = ca_create(&smc->counts, sm);
        if (r) {
                ca_destroy(&smc->old_counts);
                kfree(smc);
-               return NULL;
+               return ERR_PTR(r);
        }
 
        smc->real_sm = sm;
@@ -371,7 +371,7 @@ struct dm_space_map *dm_sm_checker_create(struct dm_space_map *sm)
                ca_destroy(&smc->counts);
                ca_destroy(&smc->old_counts);
                kfree(smc);
-               return NULL;
+               return ERR_PTR(r);
        }
 
        r = ca_commit(&smc->old_counts, &smc->counts);
@@ -379,7 +379,7 @@ struct dm_space_map *dm_sm_checker_create(struct dm_space_map *sm)
                ca_destroy(&smc->counts);
                ca_destroy(&smc->old_counts);
                kfree(smc);
-               return NULL;
+               return ERR_PTR(r);
        }
 
        return &smc->sm;
@@ -391,25 +391,25 @@ struct dm_space_map *dm_sm_checker_create_fresh(struct dm_space_map *sm)
        int r;
        struct sm_checker *smc;
 
-       if (!sm)
-               return NULL;
+       if (IS_ERR_OR_NULL(sm))
+               return ERR_PTR(-EINVAL);
 
        smc = kmalloc(sizeof(*smc), GFP_KERNEL);
        if (!smc)
-               return NULL;
+               return ERR_PTR(-ENOMEM);
 
        memcpy(&smc->sm, &ops_, sizeof(smc->sm));
        r = ca_create(&smc->old_counts, sm);
        if (r) {
                kfree(smc);
-               return NULL;
+               return ERR_PTR(r);
        }
 
        r = ca_create(&smc->counts, sm);
        if (r) {
                ca_destroy(&smc->old_counts);
                kfree(smc);
-               return NULL;
+               return ERR_PTR(r);
        }
 
        smc->real_sm = sm;

diff --git a/drivers/md/persistent-data/dm-space-map-disk.c b/drivers/md/persistent-data/dm-space-map-disk.c
index fc469ba..3d0ed53 100644 (file)
--- a/drivers/md/persistent-data/dm-space-map-disk.c
+++ b/drivers/md/persistent-data/dm-space-map-disk.c
@@ -290,7 +290,16 @@ struct dm_space_map *dm_sm_disk_create(struct dm_transaction_manager *tm,
                                       dm_block_t nr_blocks)
 {
        struct dm_space_map *sm = dm_sm_disk_create_real(tm, nr_blocks);
-       return dm_sm_checker_create_fresh(sm);
+       struct dm_space_map *smc;
+
+       if (IS_ERR_OR_NULL(sm))
+               return sm;
+
+       smc = dm_sm_checker_create_fresh(sm);
+       if (IS_ERR(smc))
+               dm_sm_destroy(sm);
+
+       return smc;
 }
 EXPORT_SYMBOL_GPL(dm_sm_disk_create);
 

diff --git a/drivers/md/persistent-data/dm-transaction-manager.c b/drivers/md/persistent-data/dm-transaction-manager.c
index 02bf78e..e5604b3 100644 (file)
--- a/drivers/md/persistent-data/dm-transaction-manager.c
+++ b/drivers/md/persistent-data/dm-transaction-manager.c
@@ -347,8 +347,10 @@ static int dm_tm_create_internal(struct dm_block_manager *bm,
                }
 
                *sm = dm_sm_checker_create(inner);
-               if (!*sm)
+               if (IS_ERR(*sm)) {
+                       r = PTR_ERR(*sm);
                        goto bad2;
+               }
 
        } else {
                r = dm_bm_write_lock(dm_tm_get_bm(*tm), sb_location,
@@ -367,8 +369,10 @@ static int dm_tm_create_internal(struct dm_block_manager *bm,
                }
 
                *sm = dm_sm_checker_create(inner);
-               if (!*sm)
+               if (IS_ERR(*sm)) {
+                       r = PTR_ERR(*sm);
                        goto bad2;
+               }
        }
 
        return 0;