nvdimm/btt: Free arenas on btt_init() error paths

The arenas allocated by discover_arenas() or create_arenas() are not
freed on some error paths in btt_init(). This leaks memory when BTT
initialization fails.

Call free_arenas() from the affected error paths to release the
allocations.

[ as: commit message and log edits ]

Fixes: 5212e11 ("nd_btt: atomic sector updates")
Cc: stable@vger.kernel.org
Signed-off-by: Abdun Nihaal <nihaal@cse.iitm.ac.in>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Link: https://patch.msgid.link/20260519-nvdimmleaks-v1-2-592300fb7a43@cse.iitm.ac.in
Signed-off-by: Alison Schofield <alison.schofield@intel.com>

Author: Abdun Nihaal

drivers/nvdimm/btt.c

@@ -1592,7 +1592,7 @@ static struct btt *btt_init(struct nd_btt *nd_btt, unsigned long long rawsize,
 	if (btt->init_state != INIT_READY && nd_region->ro) {
 		dev_warn(dev, "%s is read-only, unable to init btt metadata\n",
 				dev_name(&nd_region->dev));
-		return NULL;
+		goto err;
 	} else if (btt->init_state != INIT_READY) {
 		btt->num_arenas = (rawsize / ARENA_MAX_SIZE) +
 			((rawsize % ARENA_MAX_SIZE) ? 1 : 0);
@@ -1602,25 +1602,28 @@ static struct btt *btt_init(struct nd_btt *nd_btt, unsigned long long rawsize,
 		ret = create_arenas(btt);
 		if (ret) {
 			dev_info(dev, "init: create_arenas: %d\n", ret);
-			return NULL;
+			goto err;
 		}
 
 		ret = btt_meta_init(btt);
 		if (ret) {
 			dev_err(dev, "init: error in meta_init: %d\n", ret);
-			return NULL;
+			goto err;
 		}
 	}
 
 	ret = btt_blk_init(btt);
 	if (ret) {
 		dev_err(dev, "init: error in blk_init: %d\n", ret);
-		return NULL;
+		goto err;
 	}
 
 	btt_debugfs_init(btt);
 
 	return btt;
+err:
+	free_arenas(btt);
+	return NULL;
 }
 
 /**