From: Eric Biggers ebiggers@google.com

As described in "fscrypt: add fscrypt_is_nokey_name()", it's possible to create a duplicate filename in an encrypted directory by creating a file concurrently with adding the directory's encryption key.

Fix this bug on f2fs by rejecting no-key dentries in f2fs_add_link().

Note that the weird check for the current task in f2fs_do_add_link() seems to make this bug difficult to reproduce on f2fs.

Fixes: 9ea97163c6da ("f2fs crypto: add filename encryption for f2fs_add_link") Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers ebiggers@google.com --- fs/f2fs/f2fs.h | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index cb700d797296..9a321c52face 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -3251,6 +3251,8 @@ bool f2fs_empty_dir(struct inode *dir);

static inline int f2fs_add_link(struct dentry *dentry, struct inode *inode) { + if (fscrypt_is_nokey_name(dentry)) + return -ENOKEY; return f2fs_do_add_link(d_inode(dentry->d_parent), &dentry->d_name, inode, inode->i_ino, inode->i_mode); }