Rémi Bernon : msvcrt: Write memory forward in memset.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 7c046c7afd4253daa9cd8dbb6b2f466f128fecc9
URL:    https://source.winehq.org/git/wine.git/?a=commit;h=7c046c7afd4253daa9cd8dbb6b2f466f128fecc9

Author: Rémi Bernon <rbernon at codeweavers.com>
Date:   Thu Oct 21 10:44:29 2021 +0200

msvcrt: Write memory forward in memset.

Instead of going backward, which breaks the Linux kernel transparent
huge pages allocation assumptions.

This can be reproduced by calling memset on large, newly allocated,
memory regions.

Signed-off-by: Rémi Bernon <rbernon at codeweavers.com>
Signed-off-by: Piotr Caban <piotr at codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard at winehq.org>

---

 dlls/msvcrt/string.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/dlls/msvcrt/string.c b/dlls/msvcrt/string.c
index 5655fbfe68a..48d44d3b72e 100644
--- a/dlls/msvcrt/string.c
+++ b/dlls/msvcrt/string.c
@@ -2857,13 +2857,14 @@ void * __cdecl memcpy(void *dst, const void *src, size_t n)
 
 static inline void memset_aligned_32(unsigned char *d, uint64_t v, size_t n)
 {
-    while (n >= 32)
-    {
-        *(uint64_t *)(d + n - 32) = v;
-        *(uint64_t *)(d + n - 24) = v;
-        *(uint64_t *)(d + n - 16) = v;
-        *(uint64_t *)(d + n -  8) = v;
-        n -= 32;
+    unsigned char *end = d + n;
+    while (d < end)
+    {
+        *(uint64_t *)(d + 0) = v;
+        *(uint64_t *)(d + 8) = v;
+        *(uint64_t *)(d + 16) = v;
+        *(uint64_t *)(d + 24) = v;
+        d += 32;
     }
 }