ovl: fix reference counting in ovl_mmap error path

BugLink: https://bugs.launchpad.net/bugs/1927535
commit 2896900e22f8212606a1837d89a6bbce314ceeda upstream.

mmap_region() now calls fput() on the vma->vm_file.

Fix this by using vma_set_file() so it doesn't need to be handled
manually here any more.

Link: https://lkml.kernel.org/r/20210421132012.82354-2-christian.koenig@amd.com
Fixes: 1527f926fd04 ("mm: mmap: fix fput in error path v2")
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Jan Harkes <jaharkes@cs.cmu.edu>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: <stable@vger.kernel.org>	[5.11+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>

diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index f04948931889b3c360268ac08d07d7500fe9912d..bad38d34f8b2be64a8bd7e0237301070bbf03333 100644 (file)
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -432,20 +432,11 @@ static int ovl_mmap(struct file *file, struct vm_area_struct *vma)
        if (WARN_ON(file != vma->vm_file))
                return -EIO;
 
-       vma->vm_file = get_file(realfile);
+       vma_set_file(vma, realfile);
 
        old_cred = ovl_override_creds(file_inode(file)->i_sb);
        ret = call_mmap(vma->vm_file, vma);
        revert_creds(old_cred);
-
-       if (ret) {
-               /* Drop reference count from new vm_file value */
-               fput(realfile);
-       } else {
-               /* Drop reference count from previous vm_file value */
-               fput(file);
-       }
-
        ovl_file_accessed(file);
 
        return ret;