From: Dan Carpenter <dan.carpenter@oracle.com>
To: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Wei Yongjun <weiyongjun1@huawei.com>,
Jason Gunthorpe <jgg@ziepe.ca>,
Ralph Campbell <rcampbell@nvidia.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
kernel-janitors@vger.kernel.org
Subject: [PATCH v2] mm/hmm/test: use after free in dmirror_allocate_chunk()
Date: Thu, 24 Sep 2020 16:46:51 +0300 [thread overview]
Message-ID: <20200924134651.GA1586456@mwanda> (raw)
In-Reply-To: <c25729e4-8a53-07e3-ae98-d77919f3ac21@nvidia.com>
The error handling code does this:
err_free:
kfree(devmem);
^^^^^^^^^^^^^
err_release:
release_mem_region(devmem->pagemap.range.start, range_len(&devmem->pagemap.range));
^^^^^^^^
The problem is that when we use "devmem->pagemap.range.start" the
"devmem" pointer is either NULL or freed.
Neither the allocation nor the call to request_free_mem_region() has to
be done under the lock so I moved those to the start of the function.
Fixes: b2ef9f5a5cb3 ("mm/hmm/test: add selftest driver for HMM")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
v2: The first version introduced a locking bug
lib/test_hmm.c | 44 ++++++++++++++++++++++----------------------
1 file changed, 22 insertions(+), 22 deletions(-)
diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index c8133f50160b..e151a7f10519 100644
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -459,6 +459,22 @@ static bool dmirror_allocate_chunk(struct dmirror_device *mdevice,
unsigned long pfn_last;
void *ptr;
+ devmem = kzalloc(sizeof(*devmem), GFP_KERNEL);
+ if (!devmem)
+ return -ENOMEM;
+
+ res = request_free_mem_region(&iomem_resource, DEVMEM_CHUNK_SIZE,
+ "hmm_dmirror");
+ if (IS_ERR(res))
+ goto err_devmem;
+
+ devmem->pagemap.type = MEMORY_DEVICE_PRIVATE;
+ devmem->pagemap.range.start = res->start;
+ devmem->pagemap.range.end = res->end;
+ devmem->pagemap.nr_range = 1;
+ devmem->pagemap.ops = &dmirror_devmem_ops;
+ devmem->pagemap.owner = mdevice;
+
mutex_lock(&mdevice->devmem_lock);
if (mdevice->devmem_count == mdevice->devmem_capacity) {
@@ -471,30 +487,14 @@ static bool dmirror_allocate_chunk(struct dmirror_device *mdevice,
sizeof(new_chunks[0]) * new_capacity,
GFP_KERNEL);
if (!new_chunks)
- goto err;
+ goto err_release;
mdevice->devmem_capacity = new_capacity;
mdevice->devmem_chunks = new_chunks;
}
- res = request_free_mem_region(&iomem_resource, DEVMEM_CHUNK_SIZE,
- "hmm_dmirror");
- if (IS_ERR(res))
- goto err;
-
- devmem = kzalloc(sizeof(*devmem), GFP_KERNEL);
- if (!devmem)
- goto err_release;
-
- devmem->pagemap.type = MEMORY_DEVICE_PRIVATE;
- devmem->pagemap.range.start = res->start;
- devmem->pagemap.range.end = res->end;
- devmem->pagemap.nr_range = 1;
- devmem->pagemap.ops = &dmirror_devmem_ops;
- devmem->pagemap.owner = mdevice;
-
ptr = memremap_pages(&devmem->pagemap, numa_node_id());
if (IS_ERR(ptr))
- goto err_free;
+ goto err_release;
devmem->mdevice = mdevice;
pfn_first = devmem->pagemap.range.start >> PAGE_SHIFT;
@@ -525,12 +525,12 @@ static bool dmirror_allocate_chunk(struct dmirror_device *mdevice,
return true;
-err_free:
- kfree(devmem);
err_release:
- release_mem_region(devmem->pagemap.range.start, range_len(&devmem->pagemap.range));
-err:
mutex_unlock(&mdevice->devmem_lock);
+ release_mem_region(devmem->pagemap.range.start, range_len(&devmem->pagemap.range));
+err_devmem:
+ kfree(devmem);
+
return false;
}
--
2.28.0
next prev parent reply other threads:[~2020-09-24 13:47 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-22 8:12 [PATCH] mm/hmm/test: use after free in dmirror_allocate_chunk() Dan Carpenter
2020-09-22 17:31 ` Ralph Campbell
2020-09-24 13:46 ` Dan Carpenter [this message]
2020-09-24 19:25 ` [PATCH v2] " Ralph Campbell
2020-09-24 13:47 ` [PATCH] " Dan Carpenter
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