Re: [ros-dev] [ros-diffs] [jgardou] 64525: [KERNEL32] - Always allocate a guard page at the bottom of the stack. It doesn't depend on it being reserved or committed, it just has to be here.

[Alex Ionescu]

Hi,

This code changes Windows behavior.

Best regards,
Alex Ionescu

On Sat, Oct 4, 2014 at 1:25 PM, [e-mail] wrote:
> Author: jgardou
> Date: Sat Oct  4 20:25:35 2014
> New Revision: 64525
>
> URL: http://svn.reactos.org/svn/reactos?rev=64525&view=rev
> Log:
> [KERNEL32]
> Always allocate a guard page at the bottom of the stack.
>
> It doesn't depend on it being reserved or committed, it just has to be
> here.
>
> Modified:
>     trunk/reactos/dll/win32/kernel32/client/utils.c
>
> Modified: trunk/reactos/dll/win32/kernel32/client/utils.c
> URL:
> http://svn.reactos.org/svn/reactos/trunk/reactos/dll/win32/kernel32/client/u...
>
> ==============================================================================
> --- trunk/reactos/dll/win32/kernel32/client/utils.c     [iso-8859-1]
> (original)
> +++ trunk/reactos/dll/win32/kernel32/client/utils.c     [iso-8859-1] Sat
> Oct  4 20:25:35 2014
> @@ -358,7 +358,6 @@
>      NTSTATUS Status;
>      PIMAGE_NT_HEADERS Headers;
>      ULONG_PTR Stack;
> BOOLEAN UseGuard;
> ULONG PageSize, Dummy, AllocationGranularity;
> SIZE_T StackReserveHeader, StackCommitHeader, GuardPageSize,
>
> GuaranteedStackCommit;
>      DPRINT("BaseCreateStack (hProcess: %p, Max: %lx, Current: %lx)\n",
> @@ -426,18 +425,6 @@
>      /* Update the Stack Position */
>      Stack += StackReserve - StackCommit;
> /* Check if we will need a guard page */
> if (StackReserve > StackCommit)
> {
>    Stack -= PageSize;
>    StackCommit += PageSize;
>    UseGuard = TRUE;
> }
> else
> {
>    UseGuard = FALSE;
> }
> /* Allocate memory for the stack */
>    Status = NtAllocateVirtualMemory(hProcess,
>                                     (PVOID*)&Stack,
>
> @@ -457,25 +444,21 @@
>      InitialTeb->StackLimit = (PVOID)Stack;
>  /* Create a guard page */
> if (UseGuard)
> {
>    /* Set the guard page */
>    GuardPageSize = PAGE_SIZE;
>    Status = NtProtectVirtualMemory(hProcess,
>                                    (PVOID*)&Stack,
>                                    &GuardPageSize,
>                                    PAGE_GUARD | PAGE_READWRITE,
>                                    &Dummy);
>    if (!NT_SUCCESS(Status))
>    {
>        DPRINT1("Failure to set guard page\n");
>        return Status;
>    }
>    /* Update the Stack Limit keeping in mind the Guard Page */
>    InitialTeb->StackLimit =
>
> (PVOID)((ULONG_PTR)InitialTeb->StackLimit +
>                                     GuardPageSize);
> }
>
> GuardPageSize = PageSize;
>
> Status = NtProtectVirtualMemory(hProcess,
>                                (PVOID*)&Stack,
>                                &GuardPageSize,
>                                PAGE_GUARD | PAGE_READWRITE,
>                                &Dummy);
>
> if (!NT_SUCCESS(Status))
>
> {
>    DPRINT1("Failure to set guard page\n");
>    return Status;
>
> }
>
> /* Update the Stack Limit keeping in mind the Guard Page */
>
> InitialTeb->StackLimit = (PVOID)((ULONG_PTR)InitialTeb->StackLimit +
>                                 GuardPageSize);
>
> /* We are done! */
>    return STATUS_SUCCESS;