From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7D0FF1DDF5; Thu, 15 Aug 2024 13:29:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723728570; cv=none; b=kVcCzmEzhbAsGqkkaN12PQ7UevW4kOYbs18+zQCiqmy2tfEwXgdJ6tzx2cwIcpQ/4ufWUC6PBCp+MiXFtsr+PJapB3mCQcn880YFLz38P9Nzp7rqqb3RXqMsp6OlvI61AtAPX3CERin/rgn6dghD1Enj71WD8mJJI0NbYGOaSkI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723728570; c=relaxed/simple; bh=R6q2mV44HDeLwUFgsSLweWfuVtA0119Tebh7ZlkWor8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=qisKNqRHCXX7uRssUHzzYOj3zGepiQijS+SbmbJlkjdqm9hVY31TrGTGDlvB00O2typPJqXijlXvOO1mIbXbz8A38IxhMn4Kk/qIcWYDYf/46vZOnmGqUS/9DqQQFD370veHgamIJVNUE5AGWccmOcsaXYF+8cCCJ9Ac5lyGGf4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=nDTZ+yGg; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="nDTZ+yGg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DF77DC32786; Thu, 15 Aug 2024 13:29:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1723728570; bh=R6q2mV44HDeLwUFgsSLweWfuVtA0119Tebh7ZlkWor8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nDTZ+yGgMprHG2ny2S9HH8AzQL4AQBf6ffiuwBiLZBUFVGMIhjBpC0riLiVwNsnss 7ZOuwnvC8Rb2lgFKe+APM9qqDdj0EI2A2TvVNGsVEfqI1f9gP8BjXTI10O95ZPUCxo bkGzrAZ79BYlQGr6ltjuDAeOA6YqiAW36ZFoNDa0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+9c1fe13fcb51574b249b@syzkaller.appspotmail.com, Hugh Dickins , Jan Kara , Theodore Tso , Sasha Levin Subject: [PATCH 4.19 040/196] ext4: avoid writing unitialized memory to disk in EA inodes Date: Thu, 15 Aug 2024 15:22:37 +0200 Message-ID: <20240815131853.619190700@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240815131852.063866671@linuxfoundation.org> References: <20240815131852.063866671@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jan Kara [ Upstream commit 65121eff3e4c8c90f8126debf3c369228691c591 ] If the extended attribute size is not a multiple of block size, the last block in the EA inode will have uninitialized tail which will get written to disk. We will never expose the data to userspace but still this is not a good practice so just zero out the tail of the block as it isn't going to cause a noticeable performance overhead. Fixes: e50e5129f384 ("ext4: xattr-in-inode support") Reported-by: syzbot+9c1fe13fcb51574b249b@syzkaller.appspotmail.com Reported-by: Hugh Dickins Signed-off-by: Jan Kara Link: https://patch.msgid.link/20240613150234.25176-1-jack@suse.cz Signed-off-by: Theodore Ts'o Signed-off-by: Sasha Levin --- fs/ext4/xattr.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c index dc42a8fba0d22..e9299f769dbfe 100644 --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -1420,6 +1420,12 @@ static int ext4_xattr_inode_write(handle_t *handle, struct inode *ea_inode, goto out; memcpy(bh->b_data, buf, csize); + /* + * Zero out block tail to avoid writing uninitialized memory + * to disk. + */ + if (csize < blocksize) + memset(bh->b_data + csize, 0, blocksize - csize); set_buffer_uptodate(bh); ext4_handle_dirty_metadata(handle, ea_inode, bh); -- 2.43.0