The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x 135496c208ba26fd68cdef10b64ed7a91ac9a7ff # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024110947-footbath-census-7efa@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 135496c208ba26fd68cdef10b64ed7a91ac9a7ff Mon Sep 17 00:00:00 2001 From: Ming-Hung Tsai mtsai@redhat.com Date: Tue, 22 Oct 2024 15:12:49 +0800 Subject: [PATCH] dm cache: fix flushing uninitialized delayed_work on cache_ctr error
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
diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c index 90772b42c234..68e9a1abd303 100644 --- a/drivers/md/dm-cache-target.c +++ b/drivers/md/dm-cache-target.c @@ -1905,16 +1905,13 @@ static void check_migrations(struct work_struct *ws) * 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);
@@ -1942,13 +1939,22 @@ 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) @@ -2561,7 +2567,7 @@ static int cache_create(struct cache_args *ca, struct cache **result) *result = cache; return 0; bad: - destroy(cache); + __destroy(cache); return r; }
@@ -2612,7 +2618,7 @@ static int cache_ctr(struct dm_target *ti, unsigned int argc, char **argv)
r = copy_ctr_args(cache, argc - 3, (const char **)argv + 3); if (r) { - destroy(cache); + __destroy(cache); goto out; }