[reactos] 01/01: [WIN32SS][NTUSER] Fix an integer underflow within scrollbar info setting

[George Bișoc]

https://git.reactos.org/?p=reactos.git;a=commitdiff;h=ffea5152e607512f09efdb...

commit ffea5152e607512f09efdb0bd02499e481877f59
Author:     George Bișoc [e-mail]
AuthorDate: Sun Apr 25 15:56:39 2021 +0200
Commit:     George Bișoc [e-mail]
CommitDate: Sun Apr 25 15:56:39 2021 +0200

[WIN32SS][NTUSER] Fix an integer underflow within scrollbar info setting

Thanks goes to I_Kill_Bugs for the patch (and partly to Kyle Katarn for the PR) and Hermes for tweaking the patch code. Had to make a commit myself as the PR author's account is deleted.

Signed-off by: I_Kill_Bugs (original patch author)
    Signed-off by: Kyle Katarn [e-mail]
    Signed-off by: Hermès BÉLUSCA - MAÏTO [e-mail]
---
 win32ss/user/ntuser/scrollbar.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/win32ss/user/ntuser/scrollbar.c b/win32ss/user/ntuser/scrollbar.c
index ece40873a49..75d499b25e6 100644
--- a/win32ss/user/ntuser/scrollbar.c
+++ b/win32ss/user/ntuser/scrollbar.c
@@ -597,7 +597,7 @@ co_IntSetScrollInfo(PWND Window, INT nBar, LPCSCROLLINFO lpsi, BOOL bRedraw)
    if (lpsi->fMask & (SIF_RANGE | SIF_PAGE | SIF_DISABLENOSCROLL))
    {
       new_flags = Window->pSBInfo->WSBflags;
-      if (Info->nMin >= (int)(Info->nMax - max(Info->nPage - 1, 0)))
+      if (Info->nMin + (int)max(Info->nPage, 1) > Info->nMax)
       {
          /* Hide or disable scroll-bar */
          if (lpsi->fMask & SIF_DISABLENOSCROLL)