commit 43c90450174ab8839c05702ac01c4092f5b6cd19
author Elliott Hughes <enh@google.com> Fri Nov 20 17:19:19 2015 +0000
committer Gerrit Code Review <noreply-gerritcodereview@google.com> Fri Nov 20 17:19:19 2015 +0000
tree 90447b12715a95240614e440be8cbb7c42d191a1
parent f30170dfa514266a0bf007091aa54a866920208c
parent ee67dd75e215f88e5632c05c7e7e7c7d30910359

Merge "mmap: fix calculation of is_private_anonymous variable"

libc/bionic/mmap.cpp

diff --git a/libc/bionic/mmap.cpp b/libc/bionic/mmap.cpp
index 8301445..57a8cdf 100644
--- a/libc/bionic/mmap.cpp
+++ b/libc/bionic/mmap.cpp
@@ -54,10 +54,14 @@
     return MAP_FAILED;
   }
 
-  bool is_private_anonymous = (flags & (MAP_PRIVATE | MAP_ANONYMOUS)) != 0;
+  bool is_private_anonymous =
+      (flags & (MAP_PRIVATE | MAP_ANONYMOUS)) == (MAP_PRIVATE | MAP_ANONYMOUS);
+  bool is_stack_or_grows_down = (flags & (MAP_STACK | MAP_GROWSDOWN)) != 0;
+
   void* result = __mmap2(addr, size, prot, flags, fd, offset >> MMAP2_SHIFT);
 
-  if (result != MAP_FAILED && kernel_has_MADV_MERGEABLE && is_private_anonymous) {
+  if (result != MAP_FAILED && kernel_has_MADV_MERGEABLE &&
+      is_private_anonymous && !is_stack_or_grows_down) {
     ErrnoRestorer errno_restorer;
     int rc = madvise(result, size, MADV_MERGEABLE);
     if (rc == -1 && errno == EINVAL) {