[PATCH 0/1] MR8043: ntdll: Align records retrieved by SystemProcessInformation.

[Bernhard Übelacker]

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=55928

There is no application known, which fails because of this, it just triggers UndefinedBehaviorSanitizer.

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/8043

[PATCH 1/1] ntdll: Align records retrieved by SystemProcessInformation.

[Bernhard Übelacker]

From: Bernhard Übelacker <bernhardu(a)mailbox.org>

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=55928
---
 dlls/ntdll/tests/info.c  | 2 ++
 dlls/ntdll/unix/system.c | 3 +++
 dlls/wow64/system.c      | 4 +++-
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/dlls/ntdll/tests/info.c b/dlls/ntdll/tests/info.c
index ac979760433..f63ddf4116e 100644
--- a/dlls/ntdll/tests/info.c
+++ b/dlls/ntdll/tests/info.c
@@ -662,6 +662,8 @@ static void test_query_process( BOOL extended )
             }
         }
 
+        ok(((INT_PTR)spi & 7) == 0, "Record is not aligned at 8 byte boundary. %p\n", spi);
+
         if (!spi->NextEntryOffset)
         {
             winetest_pop_context();
diff --git a/dlls/ntdll/unix/system.c b/dlls/ntdll/unix/system.c
index d3983c0dffb..eafc5c5b3b0 100644
--- a/dlls/ntdll/unix/system.c
+++ b/dlls/ntdll/unix/system.c
@@ -2879,6 +2879,9 @@ C_ASSERT( sizeof(struct process_info) <= sizeof(SYSTEM_PROCESS_INFORMATION) );
 
         proc_len = sizeof(*nt_process) + server_process->thread_count * thread_info_size
                      + (name_len + 1) * sizeof(WCHAR);
+#define ALIGN(n, align) (((n) + (align) - 1) & ~((align) - 1))
+        proc_len = ALIGN(proc_len, 8);
+#undef ALIGN
         *len += proc_len;
 
         if (*len <= size)
diff --git a/dlls/wow64/system.c b/dlls/wow64/system.c
index ffa82054b9a..a8eb528fc7d 100644
--- a/dlls/wow64/system.c
+++ b/dlls/wow64/system.c
@@ -176,7 +176,9 @@ static NTSTATUS put_system_proc_info( SYSTEM_PROCESS_INFORMATION32 *info32,
             if (prev) prev->NextEntryOffset = (char *)proc32 - (char *)prev;
             prev = proc32;
         }
-        outpos += proc_len + proc->ProcessName.MaximumLength;
+#define ALIGN(n, align) (((n) + (align) - 1) & ~((align) - 1))
+        outpos += ALIGN(proc_len + proc->ProcessName.MaximumLength, 8);
+#undef ALIGN
         inpos += proc->NextEntryOffset;
         if (!proc->NextEntryOffset) break;
     }
-- 
GitLab

https://gitlab.winehq.org/wine/wine/-/merge_requests/8043

[Paul Gofman (＠gofman)]

While it may be correct, it could probably use a test? The correct would be to align how (and if)  Windows does and not necessarily do what a sanitizer wants (while quite possible that Windows aligns output).

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/8043#note_103360

[Bernhard Übelacker]

On Wed May 14 15:24:06 2025 +0000, Paul Gofman wrote:
> While it may be correct, it could probably use a test? The correct would
> be to align how (and if)  Windows does and not necessarily do what a
> sanitizer wants (while quite possible that Windows aligns output).
> Thanks for looking into it. One test addition is already included to `ntdll/tests/info.c`. This test seems to be ok at windows (in this [testbot run](https://testbot.winehq.org/JobDetails.pl?Key=158267). And it failed with wine before changing the implementation.

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/8043#note_103368

[Paul Gofman (＠gofman)]

On Wed May 14 15:24:06 2025 +0000, Bernhard Übelacker wrote:
> Thanks for looking into it. One test addition is already included to
> `ntdll/tests/info.c`. This test seems to be ok at windows (in this
> [testbot run](https://testbot.winehq.org/JobDetails.pl?Key=158267). And
> it failed with wine before changing the implementation.
> Ah, great, thanks.

You probably don't want to add #define ALIGN for one time use. I'd suggest to use a variable for (initially) unaligned result instead and just align without macros (also using it like \~(ULONG_PTR)7));

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/8043#note_103382