ipv6: sr: fix memleak in seg6_hmac_init_algo

seg6_hmac_init_algo returns without cleaning up the previous allocations
if one fails, so it's going to leak all that memory and the crypto tfms.

Update seg6_hmac_exit to only free the memory when allocated, so we can
reuse the code directly.

Fixes: bf355b8d ("ipv6: sr: add core files for SR HMAC support")
Reported-by: Sabrina Dubroca <sd@queasysnail.net>
Closes: https://lore.kernel.org/netdev/Zj3bh-gE7eT6V6aH@hog/Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Link: https://lore.kernel.org/r/20240517005435.2600277-1-liuhangbin@gmail.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

net/ipv6/seg6_hmac.c

@@ -356,6 +356,7 @@ static int seg6_hmac_init_algo(void)
 	struct crypto_shash *tfm;
 	struct shash_desc *shash;
 	int i, alg_count, cpu;
+	int ret = -ENOMEM;
 
 	alg_count = ARRAY_SIZE(hmac_algos);
 
@@ -366,12 +367,14 @@ static int seg6_hmac_init_algo(void)
 		algo = &hmac_algos[i];
 		algo->tfms = alloc_percpu(struct crypto_shash *);
 		if (!algo->tfms)
-			return -ENOMEM;
+			goto error_out;
 
 		for_each_possible_cpu(cpu) {
 			tfm = crypto_alloc_shash(algo->name, 0, 0);
-			if (IS_ERR(tfm))
-				return PTR_ERR(tfm);
+			if (IS_ERR(tfm)) {
+				ret = PTR_ERR(tfm);
+				goto error_out;
+			}
 			p_tfm = per_cpu_ptr(algo->tfms, cpu);
 			*p_tfm = tfm;
 		}
@@ -383,18 +386,22 @@ static int seg6_hmac_init_algo(void)
 
 		algo->shashs = alloc_percpu(struct shash_desc *);
 		if (!algo->shashs)
-			return -ENOMEM;
+			goto error_out;
 
 		for_each_possible_cpu(cpu) {
 			shash = kzalloc_node(shsize, GFP_KERNEL,
 					     cpu_to_node(cpu));
 			if (!shash)
-				return -ENOMEM;
+				goto error_out;
 			*per_cpu_ptr(algo->shashs, cpu) = shash;
 		}
 	}
 
 	return 0;
+
+error_out:
+	seg6_hmac_exit();
+	return ret;
 }
 
 int __init seg6_hmac_init(void)
@@ -412,22 +419,29 @@ int __net_init seg6_hmac_net_init(struct net *net)
 void seg6_hmac_exit(void)
 {
 	struct seg6_hmac_algo *algo = NULL;
+	struct crypto_shash *tfm;
+	struct shash_desc *shash;
 	int i, alg_count, cpu;
 
 	alg_count = ARRAY_SIZE(hmac_algos);
 	for (i = 0; i < alg_count; i++) {
 		algo = &hmac_algos[i];
-		for_each_possible_cpu(cpu) {
-			struct crypto_shash *tfm;
-			struct shash_desc *shash;
 
+		if (algo->shashs) {
+			for_each_possible_cpu(cpu) {
 				shash = *per_cpu_ptr(algo->shashs, cpu);
 				kfree(shash);
+			}
+			free_percpu(algo->shashs);
+		}
+
+		if (algo->tfms) {
+			for_each_possible_cpu(cpu) {
 				tfm = *per_cpu_ptr(algo->tfms, cpu);
 				crypto_free_shash(tfm);
 			}
 			free_percpu(algo->tfms);
-		free_percpu(algo->shashs);
+		}
 	}
 }
 EXPORT_SYMBOL(seg6_hmac_exit);