[newlib-cygwin] Cygwin: fix initializing MEM_EXTENDED_PARAMETER

Corinna Vinschen corinna@sourceware.org
Mon Sep 6 18:29:48 GMT 2021


https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=3d322ac930ca6d2516680fc78e3d3018cc737483

commit 3d322ac930ca6d2516680fc78e3d3018cc737483
Author: Corinna Vinschen <corinna@vinschen.de>
Date:   Mon Sep 6 20:15:43 2021 +0200

    Cygwin: fix initializing MEM_EXTENDED_PARAMETER
    
    MEM_EXTENDED_PARAMETER consists of a 64 bit bitfield which contains
    the Type and the Reserved members.  The former usage of designated
    initializer lists initialized Type, but not Reserved.  Since that's
    not possible anymore due to a g++ 11.2 bug, Cygwin initializes the
    MEM_EXTENDED_PARAMETER structs explicitely.  This results in a
    random value in Reserved, which at least VirtualAlloc2 chokes on
    (ERROR_INVALID_PARAMETER).
    
    Set Reserved explicitely to 0 for a fix.
    
    Fixes: bdb7991db38b ("Cygwin: workaround a g++ 11.2 initialization bug")
    Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

Diff:
---
 winsup/cygwin/miscfuncs.cc | 2 ++
 winsup/cygwin/mmap.cc      | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/winsup/cygwin/miscfuncs.cc b/winsup/cygwin/miscfuncs.cc
index f4c3a1c48..b544e7125 100644
--- a/winsup/cygwin/miscfuncs.cc
+++ b/winsup/cygwin/miscfuncs.cc
@@ -519,6 +519,7 @@ class thread_allocator
     /* g++ 11.2 workaround: don't use initializer */
     MEM_EXTENDED_PARAMETER thread_ext;
     thread_ext.Type = MemExtendedParameterAddressRequirements;
+    thread_ext.Reserved = 0;
     thread_ext.Pointer = (PVOID) &thread_req;
 
     SIZE_T real_size = roundup2 (size, THREAD_STACK_SLOT);
@@ -540,6 +541,7 @@ class thread_allocator
 	/* g++ 11.2 workaround: don't use initializer */
 	MEM_EXTENDED_PARAMETER mmap_ext;
 	mmap_ext.Type = MemExtendedParameterAddressRequirements;
+	mmap_ext.Reserved = 0;
 	mmap_ext.Pointer = (PVOID) &mmap_req;
 
 	real_stackaddr = VirtualAlloc2 (GetCurrentProcess(), NULL, real_size,
diff --git a/winsup/cygwin/mmap.cc b/winsup/cygwin/mmap.cc
index 69c8c8990..2e202a047 100644
--- a/winsup/cygwin/mmap.cc
+++ b/winsup/cygwin/mmap.cc
@@ -209,6 +209,7 @@ MapView (HANDLE h, void *addr, size_t len, DWORD openflags,
       /* g++ 11.2 workaround: don't use initializer */
       MEM_EXTENDED_PARAMETER mmap_ext;
       mmap_ext.Type = MemExtendedParameterAddressRequirements;
+      mmap_ext.Reserved = 0;
       mmap_ext.Pointer = (PVOID) &mmap_req;
 
       alloc_type |= attached (prot) ? MEM_RESERVE : 0;
@@ -1629,6 +1630,7 @@ fhandler_dev_zero::mmap (caddr_t *addr, size_t len, int prot,
 	  /* g++ 11.2 workaround: don't use initializer */
 	  MEM_EXTENDED_PARAMETER mmap_ext;
 	  mmap_ext.Type = MemExtendedParameterAddressRequirements;
+	  mmap_ext.Reserved = 0;
 	  mmap_ext.Pointer = (PVOID) &mmap_req;
 
 	  base = VirtualAlloc2 (GetCurrentProcess(), *addr, len, alloc_type,


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