rsaenh: fix crash in RSAENH_CPVerifySignature if pbSignature is set to NULL or if dwSigLen is lesser than the expected value

[Mounir IDRASSI]

Hi,
This patch corrects a crash that occur in RSAENH_CPVerifySignature when
a NULL pointer pbSignature is passed to it or if the input signature is
shorter than the correct length.

Mounir IDRASSI
IDRIX - Cryptography and IT Security Experts
http://www.idrix.fr

-------------- next part --------------
>From b4d2206cba0b3ea98bea2e9ba374a95e64e7c305 Mon Sep 17 00:00:00 2001
From: Mounir IDRASSI <mounir.idrassi at idrix.fr>
Date: Tue, 15 May 2007 00:27:41 +0200
Subject: rsaenh: fix crash in RSAENH_CPVerifySignature if pbSignature is set to NULL or if dwSigLen is lesser than the expected value

---
 dlls/rsaenh/rsaenh.c       |   15 +++++++++++++++
 dlls/rsaenh/tests/rsaenh.c |   12 ++++++++++++
 2 files changed, 27 insertions(+), 0 deletions(-)

diff --git a/dlls/rsaenh/rsaenh.c b/dlls/rsaenh/rsaenh.c
index 3e7ac8e..ca9e4a9 100644
--- a/dlls/rsaenh/rsaenh.c
+++ b/dlls/rsaenh/rsaenh.c
@@ -3611,6 +3611,21 @@ BOOL WINAPI RSAENH_CPVerifySignature(HCRYPTPROV hProv, HCRYPTHASH hHash, CONST B
         return FALSE;
     }
 
+    /* in Microsoft implementation, the signature length is checked before
+     * the signature pointer.
+     */
+    if (dwSigLen != pCryptKey->dwKeyLen)
+    {
+        SetLastError(NTE_BAD_SIGNATURE);
+        return FALSE;
+    }
+
+    if (!hHash || !pbSignature)
+    {
+        SetLastError(ERROR_INVALID_PARAMETER);
+        return FALSE;
+    }
+
     if (sDescription) {
         if (!RSAENH_CPHashData(hProv, hHash, (CONST BYTE*)sDescription, 
                                 (DWORD)lstrlenW(sDescription)*sizeof(WCHAR), 0))
diff --git a/dlls/rsaenh/tests/rsaenh.c b/dlls/rsaenh/tests/rsaenh.c
index 466a43c..5d17be2 100644
--- a/dlls/rsaenh/tests/rsaenh.c
+++ b/dlls/rsaenh/tests/rsaenh.c
@@ -1043,6 +1043,18 @@ static void test_verify_signature(void) {
     ok(result, "%08x\n", GetLastError());
     if (!result) return;
 
+    /*check that a NULL pointer signature is correctly handled*/
+    result = CryptVerifySignature(hHash, NULL, 128, hPubSignKey, NULL, 0);
+    ok(!result && ERROR_INVALID_PARAMETER == GetLastError(),
+     "Expected ERROR_INVALID_PARAMETER error, got %08x\n", GetLastError());
+    if (result) return;
+
+    /* check that we get a bad signature error when the signature is too short*/
+    result = CryptVerifySignature(hHash, abSignatureMD2, 64, hPubSignKey, NULL, 0);
+    ok(!result && NTE_BAD_SIGNATURE == GetLastError(),
+     "Expected NTE_BAD_SIGNATURE error, got %08x\n", GetLastError());
+    if (result) return;
+
     result = CryptVerifySignature(hHash, abSignatureMD2, 128, hPubSignKey, NULL, 0);
     ok(result, "%08x\n", GetLastError());
     if (!result) return;
-- 
1.4.4.2