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From: Christoph Hellwig <hch@lst.de>
To: "Dan Williams" <dan.j.williams@intel.com>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Jason Gunthorpe" <jgg@mellanox.com>,
	"Ben Skeggs" <bskeggs@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>,
	linux-mm@kvack.org, nouveau@lists.freedesktop.org,
	dri-devel@lists.freedesktop.org, linux-nvdimm@lists.01.org,
	linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
	John Hubbard <jhubbard@nvidia.com>,
	Souptick Joarder <jrdr.linux@gmail.com>,
	Ralph Campbell <rcampbell@nvidia.com>,
	Philip Yang <Philip.Yang@amd.com>
Subject: [PATCH 15/22] mm/hmm: Poison hmm_range during unregister
Date: Mon,  1 Jul 2019 08:20:13 +0200	[thread overview]
Message-ID: <20190701062020.19239-16-hch@lst.de> (raw)
In-Reply-To: <20190701062020.19239-1-hch@lst.de>

From: Jason Gunthorpe <jgg@mellanox.com>

Trying to misuse a range outside its lifetime is a kernel bug. Use poison
bytes to help detect this condition. Double unregister will reliably crash.

Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Jérôme Glisse <jglisse@redhat.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Acked-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Tested-by: Philip Yang <Philip.Yang@amd.com>
---
 mm/hmm.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/mm/hmm.c b/mm/hmm.c
index 2ef14b2b5505..c30aa9403dbe 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -925,19 +925,21 @@ void hmm_range_unregister(struct hmm_range *range)
 {
 	struct hmm *hmm = range->hmm;
 
-	/* Sanity check this really should not happen. */
-	if (hmm == NULL || range->end <= range->start)
-		return;
-
 	mutex_lock(&hmm->lock);
 	list_del_init(&range->list);
 	mutex_unlock(&hmm->lock);
 
 	/* Drop reference taken by hmm_range_register() */
-	range->valid = false;
 	mmput(hmm->mm);
 	hmm_put(hmm);
-	range->hmm = NULL;
+
+	/*
+	 * The range is now invalid and the ref on the hmm is dropped, so
+	 * poison the pointer.  Leave other fields in place, for the caller's
+	 * use.
+	 */
+	range->valid = false;
+	memset(&range->hmm, POISON_INUSE, sizeof(range->hmm));
 }
 EXPORT_SYMBOL(hmm_range_unregister);
 
-- 
2.20.1


  parent reply	other threads:[~2019-07-01  6:21 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-01  6:19 dev_pagemap related cleanups v4 Christoph Hellwig
2019-07-01  6:19 ` [PATCH 01/22] mm/hmm.c: suppress compilation warnings when CONFIG_HUGETLB_PAGE is not set Christoph Hellwig
2019-07-01  6:20 ` [PATCH 02/22] mm/hmm: update HMM documentation Christoph Hellwig
2019-07-01  6:20 ` [PATCH 03/22] mm/hmm: clean up some coding style and comments Christoph Hellwig
2019-07-01  6:20 ` [PATCH 04/22] mm/hmm: support automatic NUMA balancing Christoph Hellwig
2019-07-01  6:20 ` [PATCH 05/22] mm/hmm: Only set FAULT_FLAG_ALLOW_RETRY for non-blocking Christoph Hellwig
2019-07-01  6:20 ` [PATCH 06/22] mm/hmm: fix use after free with struct hmm in the mmu notifiers Christoph Hellwig
2019-07-01  6:20 ` [PATCH 07/22] mm/hmm: Use hmm_mirror not mm as an argument for hmm_range_register Christoph Hellwig
2019-07-01  6:20 ` [PATCH 08/22] mm/hmm: Hold a mmgrab from hmm to mm Christoph Hellwig
2019-07-01  6:20 ` [PATCH 09/22] mm/hmm: Simplify hmm_get_or_create and make it reliable Christoph Hellwig
2019-07-01  6:20 ` [PATCH 10/22] mm/hmm: Remove duplicate condition test before wait_event_timeout Christoph Hellwig
2019-07-01  6:20 ` [PATCH 11/22] mm/hmm: Do not use list*_rcu() for hmm->ranges Christoph Hellwig
2019-07-01  6:20 ` [PATCH 12/22] mm/hmm: Hold on to the mmget for the lifetime of the range Christoph Hellwig
2019-07-01  6:20 ` [PATCH 13/22] mm/hmm: Use lockdep instead of comments Christoph Hellwig
2019-07-01  6:20 ` [PATCH 14/22] mm/hmm: Remove racy protection against double-unregistration Christoph Hellwig
2019-07-01  6:20 ` Christoph Hellwig [this message]
2019-07-01  6:20 ` [PATCH 16/22] mm/hmm: Remove confusing comment and logic from hmm_release Christoph Hellwig
2019-07-01  6:20 ` [PATCH 17/22] mm/hmm: Fix error flows in hmm_invalidate_range_start Christoph Hellwig
2019-07-01  6:20 ` [PATCH 18/22] mm: return valid info from hmm_range_unregister Christoph Hellwig
2019-07-03 17:22   ` Ralph Campbell
2019-07-01  6:20 ` [PATCH 19/22] mm: always return EBUSY for invalid ranges in hmm_range_{fault,snapshot} Christoph Hellwig
2019-07-02 21:43   ` Kuehling, Felix
2019-07-03 17:32   ` Ralph Campbell
2019-07-01  6:20 ` [PATCH 20/22] mm: move hmm_vma_fault to nouveau Christoph Hellwig
2019-07-03 17:48   ` Ralph Campbell
2019-07-03 17:50     ` [Nouveau] " Ilia Mirkin
2019-07-03 18:03   ` Jason Gunthorpe
2019-07-03 18:05     ` Christoph Hellwig
2019-07-03 18:13       ` Jason Gunthorpe
2019-07-01  6:20 ` [PATCH 21/22] nouveau: unlock mmap_sem on all errors from nouveau_range_fault Christoph Hellwig
2019-07-01  6:20 ` [PATCH 22/22] mm: remove the legacy hmm_pfn_* APIs Christoph Hellwig
2019-07-03 18:01   ` Jason Gunthorpe
2019-07-03 18:03     ` Christoph Hellwig
2019-07-03 18:15       ` Jason Gunthorpe
2019-07-01  8:25 ` dev_pagemap related cleanups v4 Christoph Hellwig
2019-07-02 18:42   ` Jason Gunthorpe
2019-07-02 22:45     ` Weiny, Ira
2019-07-02 22:47       ` Christoph Hellwig
2019-07-02 23:17     ` Dan Williams
2019-07-03  1:08       ` Jason Gunthorpe

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