diff options
Diffstat (limited to 'winsup/cygwin/fork.cc')
| -rw-r--r-- | winsup/cygwin/fork.cc | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/winsup/cygwin/fork.cc b/winsup/cygwin/fork.cc index faccb482c..951c7fd58 100644 --- a/winsup/cygwin/fork.cc +++ b/winsup/cygwin/fork.cc @@ -308,9 +308,21 @@ frok::parent (volatile char * volatile stack_here) ch.forker_finished = forker_finished; PTEB teb = NtCurrentTeb (); - ch.stackbottom = _tlsbase; - ch.stacktop = (void *) _tlstop; ch.stackaddr = teb->DeallocationStack; + ch.stackbottom = _tlsbase; + /* If DeallocationStack is NULL, we're running on an application-provided + stack. If so, the entire stack is committed anyway and StackLimit points + to the allocation address of the stack. Otherwise we're running on a + system-allocated stack and using StackLimit is dangerous, in case the + application encountered a stack overflow and recovered from it via + a signal handler running on an alternate stack. Since stack_here is + the address of the stack pointer we start the child with anyway, we + can set ch.stacktop to this value rounded down to page size. The + child will not need the rest of the stack anyway. */ + if (!ch.stackaddr) + ch.stacktop = _tlstop; + else + ch.stacktop = (void *) ((uintptr_t) stack_here & ~wincap.page_size ()); ch.guardsize = 0; if (&_my_tls != _main_tls) { |