From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:53756 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727062AbfBFQBI (ORCPT ); Wed, 6 Feb 2019 11:01:08 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 3EA663D09 for ; Wed, 6 Feb 2019 16:01:08 +0000 (UTC) Received: from bfoster.bos.redhat.com (dhcp-41-66.bos.redhat.com [10.18.41.66]) by smtp.corp.redhat.com (Postfix) with ESMTP id CFFEC6CF56 for ; Wed, 6 Feb 2019 16:01:07 +0000 (UTC) From: Brian Foster Subject: [PATCH] xfs: fix use after free in buf log item unlock assert Date: Wed, 6 Feb 2019 11:01:07 -0500 Message-Id: <20190206160107.63672-1-bfoster@redhat.com> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: linux-xfs@vger.kernel.org The xfs_buf_log_item ->iop_unlock() callback asserts that the buffer is unlocked when either non-stale or aborted. This assert occurs after the bli refcount has been dropped and the log item potentially freed. The aborted check is thus a potential use after free. This problem has been reproduced with KASAN enabled via generic/475. Fix up xfs_buf_item_unlock() to query aborted state before the bli reference is dropped to prevent a potential use after free. Signed-off-by: Brian Foster --- fs/xfs/xfs_buf_item.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c index 010db5f8fb00..65b32acfa0f6 100644 --- a/fs/xfs/xfs_buf_item.c +++ b/fs/xfs/xfs_buf_item.c @@ -605,6 +605,8 @@ xfs_buf_item_unlock( #if defined(DEBUG) || defined(XFS_WARN) bool ordered = bip->bli_flags & XFS_BLI_ORDERED; bool dirty = bip->bli_flags & XFS_BLI_DIRTY; + bool aborted = test_bit(XFS_LI_ABORTED, + &lip->li_flags); #endif trace_xfs_buf_item_unlock(bip); @@ -633,7 +635,7 @@ xfs_buf_item_unlock( released = xfs_buf_item_put(bip); if (hold || (stale && !released)) return; - ASSERT(!stale || test_bit(XFS_LI_ABORTED, &lip->li_flags)); + ASSERT(!stale || aborted); xfs_buf_relse(bp); } -- 2.17.2