crypto: do not free algorithm before using

In multiple functions, the algorithm fields are read after its reference is dropped through crypto_mod_put. In this case, the algorithm memory may be freed, resulting in use-after-free bugs. This patch delays the put operation until the algorithm is never used. Fixes: 79c65d1 ("crypto: cbc - Convert to skcipher") Fixes: a7d85e0 ("crypto: cfb - add support for Cipher FeedBack mode") Fixes: 043a440 ("crypto: pcbc - Convert to skcipher") Cc: <[email protected]> Signed-off-by: Pan Bian <[email protected]> Signed-off-by: Herbert Xu <[email protected]>
jerrinot · Nov 29, 2018 · e5bde04 · e5bde04
1 parent 9f4debe
commit e5bde04
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Showing 3 changed files with 12 additions and 6 deletions.
diff --git a/crypto/cbc.c b/crypto/cbc.c
@@ -140,9 +140,8 @@ static int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb)
 	spawn = skcipher_instance_ctx(inst);
 	err = crypto_init_spawn(spawn, alg, skcipher_crypto_instance(inst),
 				CRYPTO_ALG_TYPE_MASK);
-	crypto_mod_put(alg);
 	if (err)
-		goto err_free_inst;
+		goto err_put_alg;
 
 	err = crypto_inst_setname(skcipher_crypto_instance(inst), "cbc", alg);
 	if (err)
@@ -174,12 +173,15 @@ static int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb)
 	err = skcipher_register_instance(tmpl, inst);
 	if (err)
 		goto err_drop_spawn;
+	crypto_mod_put(alg);
 
 out:
 	return err;
 
 err_drop_spawn:
 	crypto_drop_spawn(spawn);
+err_put_alg:
+	crypto_mod_put(alg);
 err_free_inst:
 	kfree(inst);
 	goto out;

diff --git a/crypto/cfb.c b/crypto/cfb.c
@@ -286,9 +286,8 @@ static int crypto_cfb_create(struct crypto_template *tmpl, struct rtattr **tb)
 	spawn = skcipher_instance_ctx(inst);
 	err = crypto_init_spawn(spawn, alg, skcipher_crypto_instance(inst),
 				CRYPTO_ALG_TYPE_MASK);
-	crypto_mod_put(alg);
 	if (err)
-		goto err_free_inst;
+		goto err_put_alg;
 
 	err = crypto_inst_setname(skcipher_crypto_instance(inst), "cfb", alg);
 	if (err)
@@ -317,12 +316,15 @@ static int crypto_cfb_create(struct crypto_template *tmpl, struct rtattr **tb)
 	err = skcipher_register_instance(tmpl, inst);
 	if (err)
 		goto err_drop_spawn;
+	crypto_mod_put(alg);
 
 out:
 	return err;
 
 err_drop_spawn:
 	crypto_drop_spawn(spawn);
+err_put_alg:
+	crypto_mod_put(alg);
 err_free_inst:
 	kfree(inst);
 	goto out;

diff --git a/crypto/pcbc.c b/crypto/pcbc.c
@@ -244,9 +244,8 @@ static int crypto_pcbc_create(struct crypto_template *tmpl, struct rtattr **tb)
 	spawn = skcipher_instance_ctx(inst);
 	err = crypto_init_spawn(spawn, alg, skcipher_crypto_instance(inst),
 				CRYPTO_ALG_TYPE_MASK);
-	crypto_mod_put(alg);
 	if (err)
-		goto err_free_inst;
+		goto err_put_alg;
 
 	err = crypto_inst_setname(skcipher_crypto_instance(inst), "pcbc", alg);
 	if (err)
@@ -275,12 +274,15 @@ static int crypto_pcbc_create(struct crypto_template *tmpl, struct rtattr **tb)
 	err = skcipher_register_instance(tmpl, inst);
 	if (err)
 		goto err_drop_spawn;
+	crypto_mod_put(alg);
 
 out:
 	return err;
 
 err_drop_spawn:
 	crypto_drop_spawn(spawn);
+err_put_alg:
+	crypto_mod_put(alg);
 err_free_inst:
 	kfree(inst);
 	goto out;