Commit df31155a authored by Lorenzo Stoakes's avatar Lorenzo Stoakes Committed by Andrew Morton
Browse files

mm: assert mmap write lock held on do_mmap(), mmap_region() 

Both of these functions can be invoked outside of mm, so it is probably a
good idea to assert that the required lock is held.

Will only have an impact if CONFIG_DEBUG_VM is set, otherwise this amounts
to no change at all.

Link: https://lkml.kernel.org/r/20241212114841.55185-1-lorenzo.stoakes@oracle.com


Signed-off-by: default avatarLorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 5d45ba8c

mm/mmap.c

+4 −0
Original line number Diff line number Diff line
@@ -291,6 +291,8 @@ unsigned long do_mmap(struct file *file, unsigned long addr, 


	*populate = 0;



	mmap_assert_write_locked(mm);



	if (!len)

		return -EINVAL;
@@ -1023,6 +1025,8 @@ unsigned long mmap_region(struct file *file, unsigned long addr, 
	unsigned long ret;

	bool writable_file_mapping = false;



	mmap_assert_write_locked(current->mm);



	/* Check to see if MDWE is applicable. */

	if (map_deny_write_exec(vm_flags, vm_flags))

		return -EACCES;