PKCS#1: Do not use pointer value after freeing

The check for extra data was not dereferencing the pointer, but avoid
complaints about such uses by freeing the decrypted data only after the
check. The hexdump could have read freed memory, so that needs to be
before the freeing.

Fixes: 54ac6ff8c4a2 ("PKCS 1: Add function for checking v1.5 RSA signature")
Signed-off-by: Jouni Malinen <j@w1.fi>

diff --git a/src/tls/pkcs1.c b/src/tls/pkcs1.c
index 49e439d0276897c692927b4cbfce77c41b48c77f..7ea9cc7f32b09fdbf1cd82fb989eed4efab0730c 100644 (file)
--- a/src/tls/pkcs1.c
+++ b/src/tls/pkcs1.c
@@ -322,8 +322,6 @@ int pkcs1_v15_sig_ver(struct crypto_public_key *pk,
                return -1;
        }
 
-       os_free(decrypted);
-
        if (hdr.payload + hdr.length != decrypted + decrypted_len) {
                wpa_printf(MSG_INFO,
                           "PKCS #1: Extra data after signature - reject");
@@ -332,8 +330,12 @@ int pkcs1_v15_sig_ver(struct crypto_public_key *pk,
                            hdr.payload + hdr.length,
                            decrypted + decrypted_len - hdr.payload -
                            hdr.length);
+
+               os_free(decrypted);
                return -1;
        }
 
+       os_free(decrypted);
+
        return 0;
 }