Cygwin: mmap: fix mmap_is_attached_or_noreserve

This commit fixes two problems.  The first is that
mmap_is_attached_or_noreserve would sometimes call VirtualAlloc with
MEM_COMMIT on address ranges that were not known to have MEM_RESERVE
status.  These calls could fail, causing SIGBUS to be raised
incorrectly.  See

  https://cygwin.com/pipermail/cygwin-developers/2024-December/012725.html

for details.  Fix this by calling VirtualAlloc only on the part of the
address range that's contained in the current mmap_record.

The second problem is that the code would sometimes break out of the
main loop without knowing whether attached mappings still occur later
in the mmap_list.  This could cause SIGBUS to not be raised when it
should be.  Fix this by using "continue" rather than "break".  For
efficiency, introduce a boolean variable "nocover" that's set to true
if we discover that the address range cannot be covered by noreserve
mmap regions.

Addresses:
https://cygwin.com/pipermail/cygwin-developers/2024-December/012725.html
Fixes: 70e476d27be8 ("* include/cygwin/version.h: Bump DLL version to
1.7.0")
Signed-off-by: Ken Brown <kbrown@cornell.edu>

0 files changed, 0 insertions, 0 deletions