Fix potential memory leak in PKCS7_signatureVerify()

Fixes #25594

The code jumps to an error block when EVP_VerifyUpdate fails.
This error block does not free abuf.
In the success path the abuf memory is freed.
Move the free operation to the error block.

CLA: trivial

Reviewed-by: Dmitry Belyavskiy <beldmit@gmail.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/25596)

diff --git a/crypto/pkcs7/pk7_doit.c b/crypto/pkcs7/pk7_doit.c
index 56a37a8e4dac081525bfed70db6baa96e2b7e33c..751caf684bbca79805bf018ddffc5c34eac60969 100644 (file)
--- a/crypto/pkcs7/pk7_doit.c
+++ b/crypto/pkcs7/pk7_doit.c
@@ -1018,6 +1018,7 @@ int PKCS7_signatureVerify(BIO *bio, PKCS7 *p7, PKCS7_SIGNER_INFO *si,
     STACK_OF(X509_ATTRIBUTE) *sk;
     BIO *btmp;
     EVP_PKEY *pkey;
+    unsigned char *abuf = NULL;
     const PKCS7_CTX *ctx = ossl_pkcs7_get0_ctx(p7);
     OSSL_LIB_CTX *libctx = ossl_pkcs7_ctx_get0_libctx(ctx);
     const char *propq = ossl_pkcs7_ctx_get0_propq(ctx);
@@ -1067,7 +1068,7 @@ int PKCS7_signatureVerify(BIO *bio, PKCS7 *p7, PKCS7_SIGNER_INFO *si,
 
     sk = si->auth_attr;
     if ((sk != NULL) && (sk_X509_ATTRIBUTE_num(sk) != 0)) {
-        unsigned char md_dat[EVP_MAX_MD_SIZE], *abuf = NULL;
+        unsigned char md_dat[EVP_MAX_MD_SIZE];
         unsigned int md_len;
         int alen;
         ASN1_OCTET_STRING *message_digest;
@@ -1109,8 +1110,6 @@ int PKCS7_signatureVerify(BIO *bio, PKCS7 *p7, PKCS7_SIGNER_INFO *si,
         }
         if (!EVP_VerifyUpdate(mdc_tmp, abuf, alen))
             goto err;
-
-        OPENSSL_free(abuf);
     }
 
     os = si->enc_digest;
@@ -1128,6 +1127,7 @@ int PKCS7_signatureVerify(BIO *bio, PKCS7 *p7, PKCS7_SIGNER_INFO *si,
     }
     ret = 1;
  err:
+    OPENSSL_free(abuf);
     EVP_MD_CTX_free(mdc_tmp);
     EVP_MD_free(fetched_md);
     return ret;