svn commit: r334499 - head/sys/vm

[Alan Cox]

Author: alc
Date: Fri Jun  1 21:37:42 2018
New Revision: 334499
URL: https://svnweb.freebsd.org/changeset/base/334499

Log:
  Only a small subset of mmap(2)'s flags should be used in combination with
  the flag MAP_GUARD.  Rather than enumerating the flags that are not
  allowed, enumerate the flags that are allowed.  The list of allowed flags
  is much shorter and less likely to change.  (As an aside, one of the
  previously enumerated flags, MAP_PREFAULT, was not even a legal flag for
  mmap(2).  However, because of an earlier check within kern_mmap(), this
  misuse of MAP_PREFAULT was harmless.)
  
  Reviewed by:	kib
  MFC after:	10 days

Modified:
  head/sys/vm/vm_mmap.c

Modified: head/sys/vm/vm_mmap.c
==============================================================================
--- head/sys/vm/vm_mmap.c	Fri Jun  1 21:37:20 2018	(r334498)
+++ head/sys/vm/vm_mmap.c	Fri Jun  1 21:37:42 2018	(r334499)
@@ -241,8 +241,8 @@ kern_mmap(struct thread *td, uintptr_t addr0, size_t s
 	    (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC)) != 0)
 		return (EINVAL);
 	if ((flags & MAP_GUARD) != 0 && (prot != PROT_NONE || fd != -1 ||
-	    pos != 0 || (flags & (MAP_SHARED | MAP_PRIVATE | MAP_PREFAULT |
-	    MAP_PREFAULT_READ | MAP_ANON | MAP_STACK)) != 0))
+	    pos != 0 || (flags & ~(MAP_FIXED | MAP_GUARD | MAP_EXCL |
+	    MAP_32BIT | MAP_ALIGNMENT_MASK)) != 0))
 		return (EINVAL);
 
 	/*