[PATCH] user32: Avoid buffer overflow on long texts in winproc.

[Roman Pišl]

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=48559

Signed-off-by: Roman Pišl <rpisl at seznam.cz>
---
 dlls/user32/winproc.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/dlls/user32/winproc.c b/dlls/user32/winproc.c
index 6de650cd1e..14555f5a71 100644
--- a/dlls/user32/winproc.c
+++ b/dlls/user32/winproc.c
@@ -517,16 +517,21 @@ LRESULT WINPROC_CallProcAtoW( winproc_callback_t callback, HWND hwnd, UINT msg,
     case CB_GETLBTEXT:
         if (lParam && WINPROC_TestLBForStr( hwnd, msg ))
         {
-            WCHAR buffer[512];  /* FIXME: fixed sized buffer */
+            WCHAR *ptr, buffer[512];
+            UINT msgGetTextLen = (msg == CB_GETLBTEXT) ? CB_GETLBTEXTLEN : LB_GETTEXTLEN;
+            LRESULT len = 0;
 
-            ret = callback( hwnd, msg, wParam, (LPARAM)buffer, result, arg );
+            callback( hwnd, msgGetTextLen, wParam, 0, &len, arg );
+            if (!(ptr = get_buffer( buffer, sizeof(buffer), (len + 1) * sizeof(WCHAR) ))) break;
+            ret = callback( hwnd, msg, wParam, (LPARAM)ptr, result, arg );
             if (*result >= 0)
             {
                 DWORD len;
                 RtlUnicodeToMultiByteN( (LPSTR)lParam, ~0u, &len,
-                                        buffer, (strlenW(buffer) + 1) * sizeof(WCHAR) );
+                                        ptr, (strlenW(ptr) + 1) * sizeof(WCHAR) );
                 *result = len - 1;
             }
+            free_buffer( buffer, ptr );
         }
         else ret = callback( hwnd, msg, wParam, lParam, result, arg );
         break;
@@ -777,15 +782,20 @@ static LRESULT WINPROC_CallProcWtoA( winproc_callback_t callback, HWND hwnd, UIN
     case CB_GETLBTEXT:
         if (lParam && WINPROC_TestLBForStr( hwnd, msg ))
         {
-            char buffer[512];  /* FIXME: fixed sized buffer */
+            char *ptr, buffer[512];
+            UINT msgGetTextLen = (msg == CB_GETLBTEXT) ? CB_GETLBTEXTLEN : LB_GETTEXTLEN;
+            LRESULT len = 0;
+            callback( hwnd, msgGetTextLen, wParam, 0, &len, arg );
+            if (!(ptr = get_buffer( buffer, sizeof(buffer), len + 1 ))) break;
 
-            ret = callback( hwnd, msg, wParam, (LPARAM)buffer, result, arg );
+            ret = callback( hwnd, msg, wParam, (LPARAM)ptr, result, arg );
             if (*result >= 0)
             {
                 DWORD len;
-                RtlMultiByteToUnicodeN( (LPWSTR)lParam, ~0u, &len, buffer, strlen(buffer) + 1 );
+                RtlMultiByteToUnicodeN( (LPWSTR)lParam, ~0u, &len, ptr, strlen(ptr) + 1 );
                 *result = len / sizeof(WCHAR) - 1;
             }
+            free_buffer( buffer, ptr );
         }
         else ret = callback( hwnd, msg, wParam, lParam, result, arg );
         break;
-- 
2.20.1