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 8C9351A00CE; Thu, 15 Aug 2024 13:45:01 +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=1723729501; cv=none; b=oMBOdsVoq6lbuv8dHQSLk/qu4bCc39PSmr+Omir1Dh4VcimG/RdX1OlnQcIXbYYQV6NqkYRRdoyF8QwyLorBM4iostD2dH+JCUg+ttsZf7P00aI0uKrB395Y16zOAvMFhfrY9wS56CNpSlDl0+lYlwHkrAhTiMnkgYeI7R37474= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723729501; c=relaxed/simple; bh=C9VjhH+DUpfbPIG1iwkLL0Op/8DTk5HlMi6BMprgnfE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=pTfmcU4a3HzLqtqZc9wQ9QJFf3Aat97ayQMBku15yEyhVjJ7kGJly/3NL54Tt5bGCTB00ZyCIClCJ6VE7W5urvIqzv3AooneLaronuoEZ8pZw2zeYxDELGLHsvVHvtYS3z8obb43OxpK0lTgA13PWd+1H1J34HGa1RWdM5G09O8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ARhzPECs; 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="ARhzPECs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0F11FC32786; Thu, 15 Aug 2024 13:45:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1723729501; bh=C9VjhH+DUpfbPIG1iwkLL0Op/8DTk5HlMi6BMprgnfE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ARhzPECsZM8LmrsKstB75kFkxRn47jPxJazn3IAtIoH10fJLej453apggzNY+DfKa igoG0e7zhoeY8L9FzCiQEoI9ZC24yo3eUHfNt1k0SCZrURZ6ByTNa8ScER2Dw2QUYp 8sVhhkTun0P9Wk9uPbrqnOhO1aNF5UpxqD8qVYlI= 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 5.15 117/484] ext4: avoid writing unitialized memory to disk in EA inodes Date: Thu, 15 Aug 2024 15:19:35 +0200 Message-ID: <20240815131945.812597236@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240815131941.255804951@linuxfoundation.org> References: <20240815131941.255804951@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-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 37f3c2ebe6f82..e788f291ae86d 100644 --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -1384,6 +1384,12 @@ 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