mm: ignore MAP_EXECUTABLE in ksys_mmap_pgoff()

Let's also remove masking off MAP_EXECUTABLE from ksys_mmap_pgoff(): the
last in-tree occurrence of MAP_EXECUTABLE is now in LEGACY_MAP_MASK, which
accepts the flag e.g., for MAP_SHARED_VALIDATE; however, the flag is
ignored throughout the kernel now.

Add a comment to LEGACY_MAP_MASK stating that MAP_EXECUTABLE is ignored.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Acked-by: "Eric W. Biederman" <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Don Zickus <[email protected]>
Cc: Feng Tang <[email protected]>
Cc: Greg Ungerer <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Kevin Brodsky <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

3 files changed, 4 insertions, 2 deletions

diff --git a/include/linux/mman.h b/include/linux/mman.h
index 629cefc4ecba..ebb09a964272 100644
--- a/include/linux/mman.h
+++ b/include/linux/mman.h
@@ -31,6 +31,8 @@
 /*
  * The historical set of flags that all mmap implementations implicitly
  * support when a ->mmap_validate() op is not provided in file_operations.
+ *
+ * MAP_EXECUTABLE is completely ignored throughout the kernel.
  */
 #define LEGACY_MAP_MASK (MAP_SHARED \
 		| MAP_PRIVATE \
diff --git a/mm/mmap.c b/mm/mmap.c
index 0584e540246e..f9a61f7dc540 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1633,7 +1633,7 @@ unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
 			return PTR_ERR(file);
 	}
 
-	flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
+	flags &= ~MAP_DENYWRITE;
 
 	retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
 out_fput:
diff --git a/mm/nommu.c b/mm/nommu.c
index 85a3a68dffb6..affda71641ca 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1296,7 +1296,7 @@ unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
 			goto out;
 	}
 
-	flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
+	flags &= ~MAP_DENYWRITE;
 
 	retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);