unix: pass PROT_MPROTECT(PROT_READ|PROT_WRITE) to initial Mmap on netbsd
On NetBSD PAX mprotect prohibits setting protection bits
missing from the original mmap call unless explicitly
requested with PROT_MPROTECT.
Fixes golang/go#58660
Change-Id: I1e97e920bc617ed1674855adaae5047638a30394
Reviewed-on: https://go-review.googlesource.com/c/sys/+/470775
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
Auto-Submit: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Than McIntosh <thanm@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
diff --git a/unix/mmap_unix_test.go b/unix/mmap_unix_test.go
index a2ec6c8..d51f690 100644
--- a/unix/mmap_unix_test.go
+++ b/unix/mmap_unix_test.go
@@ -15,11 +15,21 @@
)
func TestMmap(t *testing.T) {
- b, err := unix.Mmap(-1, 0, unix.Getpagesize(), unix.PROT_NONE, unix.MAP_ANON|unix.MAP_PRIVATE)
+ mmapProt := unix.PROT_NONE
+ mprotectProt := unix.PROT_READ | unix.PROT_WRITE
+ // On NetBSD PAX mprotect prohibits setting protection bits
+ // missing from the original mmap call unless explicitly
+ // requested with PROT_MPROTECT.
+ if runtime.GOOS == "netbsd" {
+ // PROT_MPROTECT(x) is defined as ((x) << 3):
+ // https://github.com/NetBSD/src/blob/aba449a55bf91b44bc68f542edd9afa341962b89/sys/sys/mman.h#L73
+ mmapProt = mprotectProt << 3
+ }
+ b, err := unix.Mmap(-1, 0, unix.Getpagesize(), mmapProt, unix.MAP_ANON|unix.MAP_PRIVATE)
if err != nil {
t.Fatalf("Mmap: %v", err)
}
- if err := unix.Mprotect(b, unix.PROT_READ|unix.PROT_WRITE); err != nil {
+ if err := unix.Mprotect(b, mprotectProt); err != nil {
t.Fatalf("Mprotect: %v", err)
}
