6.1-stable review patch. If anyone has any objections, please let me know.
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From: Ming-Hung Tsai mtsai@redhat.com
commit 135496c208ba26fd68cdef10b64ed7a91ac9a7ff upstream.
An unexpected WARN_ON from flush_work() may occur when cache creation fails, caused by destroying the uninitialized delayed_work waker in the error path of cache_create(). For example, the warning appears on the superblock checksum error.
Reproduce steps:
dmsetup create cmeta --table "0 8192 linear /dev/sdc 0" dmsetup create cdata --table "0 65536 linear /dev/sdc 8192" dmsetup create corig --table "0 524288 linear /dev/sdc 262144" dd if=/dev/urandom of=/dev/mapper/cmeta bs=4k count=1 oflag=direct dmsetup create cache --table "0 524288 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0"
Kernel logs:
(snip) WARNING: CPU: 0 PID: 84 at kernel/workqueue.c:4178 __flush_work+0x5d4/0x890
Fix by pulling out the cancel_delayed_work_sync() from the constructor's error path. This patch doesn't affect the use-after-free fix for concurrent dm_resume and dm_destroy (commit 6a459d8edbdb ("dm cache: Fix UAF in destroy()")) as cache_dtr is not changed.
Signed-off-by: Ming-Hung Tsai mtsai@redhat.com Fixes: 6a459d8edbdb ("dm cache: Fix UAF in destroy()") Cc: stable@vger.kernel.org Signed-off-by: Mikulas Patocka mpatocka@redhat.com Acked-by: Joe Thornber thornber@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/md/dm-cache-target.c | 24 +++++++++++++++--------- 1 file changed, 15 insertions(+), 9 deletions(-)
--- a/drivers/md/dm-cache-target.c +++ b/drivers/md/dm-cache-target.c @@ -1882,16 +1882,13 @@ static void check_migrations(struct work * This function gets called on the error paths of the constructor, so we * have to cope with a partially initialised struct. */ -static void destroy(struct cache *cache) +static void __destroy(struct cache *cache) { - unsigned int i; - mempool_exit(&cache->migration_pool);
if (cache->prison) dm_bio_prison_destroy_v2(cache->prison);
- cancel_delayed_work_sync(&cache->waker); if (cache->wq) destroy_workqueue(cache->wq);
@@ -1919,13 +1916,22 @@ static void destroy(struct cache *cache) if (cache->policy) dm_cache_policy_destroy(cache->policy);
+ bioset_exit(&cache->bs); + + kfree(cache); +} + +static void destroy(struct cache *cache) +{ + unsigned int i; + + cancel_delayed_work_sync(&cache->waker); + for (i = 0; i < cache->nr_ctr_args ; i++) kfree(cache->ctr_args[i]); kfree(cache->ctr_args);
- bioset_exit(&cache->bs); - - kfree(cache); + __destroy(cache); }
static void cache_dtr(struct dm_target *ti) @@ -2538,7 +2544,7 @@ static int cache_create(struct cache_arg *result = cache; return 0; bad: - destroy(cache); + __destroy(cache); return r; }
@@ -2589,7 +2595,7 @@ static int cache_ctr(struct dm_target *t
r = copy_ctr_args(cache, argc - 3, (const char **)argv + 3); if (r) { - destroy(cache); + __destroy(cache); goto out; }