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Cygwin: threads: use mmap area to fulfill requests for big stacks 

Otherwise big stacks have a higher probability to collide with
randomized PEBs and TEBs after fork.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This commit is contained in:
Corinna Vinschen 2020-04-07 14:09:45 +02:00
parent ece49e4090
commit aa4d960306
1 changed files with 6 additions and 4 deletions
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10
winsup/cygwin/miscfuncs.cc
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@ -515,11 +515,13 @@ public:
BOOL overflow = FALSE;
PVOID real_stackaddr = NULL;
/* If an application requests a monster stack, we fulfill this request
from outside of our pool, top down. */
/* If an application requests a monster stack, fulfill request
from mmap area. */
if (real_size > THREAD_STACK_MAX)
return VirtualAlloc (NULL, real_size, MEM_RESERVE | MEM_TOP_DOWN,
PAGE_READWRITE);
{
PVOID addr = mmap_alloc.alloc (NULL, real_size, false);
return VirtualAlloc (addr, real_size, MEM_RESERVE, PAGE_READWRITE);
}
/* Simple round-robin. Keep looping until VirtualAlloc succeeded, or
until we overflowed and hit the current address. */
for (UINT_PTR addr = current - real_size;