ovl: copy-up: don't unlock between lookup and link

e85f82ff · Miklos Szeredi <[email protected]> · 2017-06-28 13:41:22 +02:00

Nothing prevents mischief on upper layer while we are busy copying up the
data.

Move the lookup right before the looked up dentry is actually used.

Signed-off-by: Miklos Szeredi <[email protected]>
Fixes: 01ad3eb8a073 ("ovl: concurrent copy up of regular files")
Cc: <[email protected]> # v4.11

Commit: e85f82ff9b8ef503923a3be8ca6b5fd1908a7f3f
Parents: c0bc126f

Changes

1 files changed · +12 −12

File	Status	Add	Del	Content
fs/overlayfs/copy_up.c	modified	+12	−12	View file

fs/overlayfs/copy_up.c

View file

diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 7a44533..ded8bfe 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -330,15 +330,9 @@ static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir,
 		.link = link
 	};
 
-	upper = lookup_one_len(dentry->d_name.name, upperdir,
-			       dentry->d_name.len);
-	err = PTR_ERR(upper);
-	if (IS_ERR(upper))
-		goto out;
-
 	err = security_inode_copy_up(dentry, &new_creds);
 	if (err < 0)
-		goto out1;
+		goto out;
 
 	if (new_creds)
 		old_creds = override_creds(new_creds);
@@ -362,7 +356,7 @@ static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir,
 	}
 
 	if (err)
-		goto out2;
+		goto out;
 
 	if (S_ISREG(stat->mode)) {
 		struct path upperpath;
@@ -403,6 +397,14 @@ static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir,
 	if (err)
 		goto out_cleanup;
 
+	upper = lookup_one_len(dentry->d_name.name, upperdir,
+			       dentry->d_name.len);
+	if (IS_ERR(upper)) {
+		err = PTR_ERR(upper);
+		upper = NULL;
+		goto out_cleanup;
+	}
+
 	if (tmpfile)
 		err = ovl_do_link(temp, udir, upper, true);
 	else
@@ -416,17 +418,15 @@ static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir,
 
 	/* Restore timestamps on parent (best effort) */
 	ovl_set_timestamps(upperdir, pstat);
-out2:
+out:
 	dput(temp);
-out1:
 	dput(upper);
-out:
 	return err;
 
 out_cleanup:
 	if (!tmpfile)
 		ovl_cleanup(wdir, temp);
-	goto out2;
+	goto out;
 }
 
 /*