[PATCH v1 3/3] mm: ignore MAP_EXECUTABLE in ksys_mmap_pgoff()

David Hildenbrand
2021-04-21T09:35:49Z

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.

Signed-off-by: David Hildenbrand <david@redhat.com>
---
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 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 3f287599a7a3..882f8ee4af1f 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1627,7 +1627,7 @@ 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 5c9ab799c0e6..1fafe3e9d3df 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1306,7 +1306,7 @@ 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);

--
2.30.2