From 3b8db39fad98cbb1d36e079236a446fad710daea Mon Sep 17 00:00:00 2001
From: David Hildenbrand <david@redhat.com>
Date: Mon, 28 Jun 2021 19:38:35 -0700
Subject: [PATCH] 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/20210421093453.6904-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Feng Tang <feng.tang@intel.com>
Cc: Greg Ungerer <gerg@linux-m68k.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kevin Brodsky <Kevin.Brodsky@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 include/linux/mman.h | 2 ++
 mm/mmap.c            | 2 +-
 mm/nommu.c           | 2 +-
 3 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/linux/mman.h b/include/linux/mman.h
index 629cefc..ebb09a964 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 0584e54..f9a61f7 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 85a3a68..affda71 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);
 
-- 
2.7.4