From: Eric Biggers <ebiggers@google.com> commit 75d18cd1868c2aee43553723872c35d7908f240f upstream. 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 ext4 by rejecting no-key dentries in ext4_add_entry(). Note that the duplicate check in ext4_find_dest_de() sometimes prevented this bug. However in many cases it didn't, since ext4_find_dest_de() doesn't examine every dentry. Fixes: 4461471107b7 ("ext4 crypto: enable filename encryption") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20201118075609.120337-3-ebiggers@kernel.org Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- fs/ext4/namei.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index 762eb6913240..c755f47b7174 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -2111,6 +2111,9 @@ static int ext4_add_entry(handle_t *handle, struct dentry *dentry, if (!dentry->d_name.len) return -EINVAL; + if (fscrypt_is_nokey_name(dentry)) + return -ENOKEY; + retval = ext4_fname_setup_filename(dir, &dentry->d_name, 0, &fname); if (retval) return retval; -- 2.25.1