From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:58208 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755200AbeD3TYr (ORCPT ); Mon, 30 Apr 2018 15:24:47 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Theodore Tso , Andreas Dilger , Jan Kara Subject: [PATCH 3.18 01/25] ext4: set h_journal if there is a failure starting a reserved handle Date: Mon, 30 Apr 2018 12:23:08 -0700 Message-Id: <20180430183910.863189903@linuxfoundation.org> In-Reply-To: <20180430183910.801976983@linuxfoundation.org> References: <20180430183910.801976983@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Theodore Ts'o commit b2569260d55228b617bd82aba6d0db2faeeb4116 upstream. If ext4 tries to start a reserved handle via jbd2_journal_start_reserved(), and the journal has been aborted, this can result in a NULL pointer dereference. This is because the fields h_journal and h_transaction in the handle structure share the same memory, via a union, so jbd2_journal_start_reserved() will clear h_journal before calling start_this_handle(). If this function fails due to an aborted handle, h_journal will still be NULL, and the call to jbd2_journal_free_reserved() will pass a NULL journal to sub_reserve_credits(). This can be reproduced by running "kvm-xfstests -c dioread_nolock generic/475". Cc: stable@kernel.org # 3.11 Fixes: 8f7d89f36829b ("jbd2: transaction reservation support") Signed-off-by: Theodore Ts'o Reviewed-by: Andreas Dilger Reviewed-by: Jan Kara Signed-off-by: Greg Kroah-Hartman --- fs/jbd2/transaction.c | 1 + 1 file changed, 1 insertion(+) --- a/fs/jbd2/transaction.c +++ b/fs/jbd2/transaction.c @@ -515,6 +515,7 @@ int jbd2_journal_start_reserved(handle_t */ ret = start_this_handle(journal, handle, GFP_NOFS); if (ret < 0) { + handle->h_journal = journal; jbd2_journal_free_reserved(handle); return ret; }