[PATCH 0/1] MR7637: wow64: skip memcpy for null pointer

[Vitaly Lipatov (＠lav)]

It looks like according to the C spec, calling memcpy(0, 0, 0) results in undefined behavior.

See also
https://developers.redhat.com/articles/2024/12/11/making-memcpynull-null-0-w...

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=56154

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/7637

[PATCH 1/1] wow64: skip memcpy for null pointer

[Vitaly Lipatov]

From: Vitaly Lipatov <lav(a)etersoft.ru>

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=56154
---
 dlls/wow64/security.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/dlls/wow64/security.c b/dlls/wow64/security.c
index 49f4adea3c1..a7616331600 100644
--- a/dlls/wow64/security.c
+++ b/dlls/wow64/security.c
@@ -471,7 +471,7 @@ NTSTATUS WINAPI wow64_NtQueryInformationToken( UINT *args )
         if (!status)
         {
             dacl32->DefaultDacl = dacl->DefaultDacl ? PtrToUlong( dacl32 + 1 ) : 0;
-            memcpy( dacl32 + 1, dacl->DefaultDacl, ret_size - sizeof(*dacl) );
+            if (dacl->DefaultDacl) memcpy( dacl32 + 1, dacl->DefaultDacl, ret_size - sizeof(*dacl) );
         }
         if (retlen) *retlen = ret_size + sizeof(*dacl32) - sizeof(*dacl);
         return status;
-- 
GitLab

https://gitlab.winehq.org/wine/wine/-/merge_requests/7637