Re: [ros-dev] [ros-diffs] [jgardou] 66323: [KERNEL32] Revert r64525 - Always allocate a guard page at the bottom of the stack.

[Alex Ionescu]

Finally...

Best regards,
Alex Ionescu

On Mon, Feb 16, 2015 at 1:12 PM, <jgardou(a)svn.reactos.org> wrote:

>   Author: jgardou
>  Date: Mon Feb 16 21:12:51 2015
>  New Revision: 66323
>
>  URL: http://svn.reactos.org/svn/reactos?rev=66323&view=rev
>  Log:
>  [KERNEL32]
>   Revert r64525 - Always allocate a guard page at the bottom of the stack.
>
>  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/…
>
>  ==============================================================================
>  --- trunk/reactos/dll/win32/kernel32/client/utils.c     [iso-8859-1]
>  (original)
>  +++ trunk/reactos/dll/win32/kernel32/client/utils.c     [iso-8859-1] Mon
>  Feb 16 21:12:51 2015
>  @@ -358,6 +358,7 @@
>       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",
>  @@ -425,6 +426,18 @@
>       /* 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,
>  @@ -444,21 +457,25 @@
>       InitialTeb->StackLimit = (PVOID)Stack;
>
>       /* Create a guard page */
>  -    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);
>  +    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);
>  +    }
>
>       /* We are done! */
>       return STATUS_SUCCESS;
>
>
>