mm/zswap: fix error pointer free in zswap_cpu_comp_prepare()

crypto_alloc_acomp_node() may return ERR_PTR(), but the fail path checks
only for NULL and can pass an error pointer to crypto_free_acomp().  Use
IS_ERR_OR_NULL() to only free valid acomp instances.

Link: https://lkml.kernel.org/r/20251231074638.2564302-1-pbutsykin@cloudlinux.com
Fixes: 779b9955f6 ("mm: zswap: move allocations during CPU init outside the lock")
Signed-off-by: Pavel Butsykin <pbutsykin@cloudlinux.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Acked-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Acked-by: Nhat Pham <nphamcs@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/zswap.c

@@ -787,7 +787,7 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
 	return 0;
 
 fail:
-	if (acomp)
+	if (!IS_ERR_OR_NULL(acomp))
 		crypto_free_acomp(acomp);
 	kfree(buffer);
 	return ret;