* Re: [PATCH v2] mm/hmm/test: use after free in dmirror_allocate_chunk()
@ 2020-09-25 19:30 Markus Elfring
2020-09-26 12:14 ` [PATCH v3] " Dan Carpenter
0 siblings, 1 reply; 6+ messages in thread
From: Markus Elfring @ 2020-09-25 19:30 UTC (permalink / raw)
To: Dan Carpenter, linux-mm, Andrew Morton, Stephen Rothwell, Dan Williams
Cc: kernel-janitors, linux-kernel, Andy Lutomirski, Ard Biesheuvel,
Ben Skeggs, Benjamin Herrenschmidt, Borislav Petkov,
Brice Goglin, Catalin Marinas, Daniel Vetter, Dave Hansen,
Dave Jiang, David Airlie, David Hildenbrand, Greg Kroah-Hartman,
H. Peter Anvin, Ingo Molnar, Ira Weiny, Jason Gunthorpe,
Jason Gunthorpe, Jeff Moyer, Jérôme Glisse, Jia He,
Joao Martins, Jonathan Cameron, Michael Ellerman, Mike Rapoport,
Paul Mackerras, Pavel Tatashin, Peter Zijlstra,
Rafael J. Wysocki, Ralph Campbell, Thomas Gleixner, Tom Lendacky,
Vishal Verma, Wei Yang, Wei Yongjun, Will Deacon
> 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.
Can this information become relevant for another update step?
> Fixes: b2ef9f5a5cb3 ("mm/hmm/test: add selftest driver for HMM")
I find this commit reference interesting somehow.
How do you think about the commit 786ae133e07f2a6b352a0efad16b555ee45a2898
("lib: fix test_hmm.c reference after free" from 2020-06-26)
and the commit 1f9c4bb986d978a5e39153b39a71c9d098b65c5c ("mm/memremap_pages:
convert to 'struct range'" from 2020-09-23) for your update suggestion?
Regards,
Markus
^ permalink raw reply [flat|nested] 6+ messages in thread* [PATCH v3] mm/hmm/test: use after free in dmirror_allocate_chunk()
2020-09-25 19:30 [PATCH v2] mm/hmm/test: use after free in dmirror_allocate_chunk() Markus Elfring
@ 2020-09-26 12:14 ` Dan Carpenter
2020-09-26 13:10 ` Markus Elfring
2020-09-26 22:17 ` Jason Gunthorpe
0 siblings, 2 replies; 6+ messages in thread
From: Dan Carpenter @ 2020-09-26 12:14 UTC (permalink / raw)
To: Jérôme Glisse, Markus Elfring, Dan Williams
Cc: Wei Yongjun, Jason Gunthorpe, Ralph Campbell, linux-mm,
linux-kernel, kernel-janitors
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: 1f9c4bb986d9 ("mm/memremap_pages: convert to 'struct range'")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
---
v2: The first version introduced a locking bug
v3: Markus Elfring pointed out that the Fixes tag was wrong. This bug
was in the original commit and then fixed and then re-introduced. I was
quite bothered by how this bug lasted so long in the source code, but
now we know. As soon as it is introduced we fixed it.
One problem with the kernel QC process is that I think everyone marks
the bug as "old/dealt with" so it was only because I was added a new
check for resource leaks that it was found when it was re-introduced.
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
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH v3] mm/hmm/test: use after free in dmirror_allocate_chunk()
2020-09-26 12:14 ` [PATCH v3] " Dan Carpenter
@ 2020-09-26 13:10 ` Markus Elfring
2020-09-26 22:17 ` Jason Gunthorpe
1 sibling, 0 replies; 6+ messages in thread
From: Markus Elfring @ 2020-09-26 13:10 UTC (permalink / raw)
To: Dan Carpenter, Dan Williams, Jérôme Glisse
Cc: linux-mm, linux-kernel, kernel-janitors, Jason Gunthorpe,
Julia Lawall, Ralph Campbell, Wei Yongjun
> One problem with the kernel QC process is that I think everyone marks
> the bug as "old/dealt with"
Will this view trigger any more clarifications?
> so it was only because I was added a new
> check for resource leaks that it was found when it was re-introduced.
I would like to point once more out that the commit 786ae133e07f2a6b352a0efad16b555ee45a2898
("lib: fix test_hmm.c reference after free" from 2020-06-26)
indicated questionable implementation details according to a coccicheck run.
The available scripts for the semantic patch language can also remind you again
for desirable software improvements.
Examples:
* https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/coccinelle/free/kfree.cocci?id=7c7ec3226f5f33f9c050d85ec20f18419c622ad6#n2
* https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/coccinelle/null/deref_null.cocci?id=7c7ec3226f5f33f9c050d85ec20f18419c622ad6#n3
Will any more adjustments be achieved with the help of advanced source code
analysis tools?
Regards,
Markus
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH v3] mm/hmm/test: use after free in dmirror_allocate_chunk()
2020-09-26 12:14 ` [PATCH v3] " Dan Carpenter
2020-09-26 13:10 ` Markus Elfring
@ 2020-09-26 22:17 ` Jason Gunthorpe
2020-09-29 0:52 ` Andrew Morton
1 sibling, 1 reply; 6+ messages in thread
From: Jason Gunthorpe @ 2020-09-26 22:17 UTC (permalink / raw)
To: Dan Carpenter, Andrew Morton
Cc: Jérôme Glisse, Markus Elfring, Dan Williams,
Wei Yongjun, Ralph Campbell, linux-mm, linux-kernel,
kernel-janitors
On Sat, Sep 26, 2020 at 03:14:02PM +0300, Dan Carpenter wrote:
> 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: 1f9c4bb986d9 ("mm/memremap_pages: convert to 'struct range'")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
> ---
> v2: The first version introduced a locking bug
> v3: Markus Elfring pointed out that the Fixes tag was wrong. This bug
> was in the original commit and then fixed and then re-introduced. I was
> quite bothered by how this bug lasted so long in the source code, but
> now we know. As soon as it is introduced we fixed it.
>
> One problem with the kernel QC process is that I think everyone marks
> the bug as "old/dealt with" so it was only because I was added a new
> check for resource leaks that it was found when it was re-introduced.
>
> lib/test_hmm.c | 44 ++++++++++++++++++++++----------------------
> 1 file changed, 22 insertions(+), 22 deletions(-)
Hi Andrew,
I don't have have any hmm related patches this cycle, can you take
this into your tree?
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Thanks,
Jason
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH v3] mm/hmm/test: use after free in dmirror_allocate_chunk()
2020-09-26 22:17 ` Jason Gunthorpe
@ 2020-09-29 0:52 ` Andrew Morton
2020-09-29 1:25 ` Dan Williams
0 siblings, 1 reply; 6+ messages in thread
From: Andrew Morton @ 2020-09-29 0:52 UTC (permalink / raw)
To: Jason Gunthorpe
Cc: Dan Carpenter, Jérôme Glisse, Markus Elfring,
Dan Williams, Wei Yongjun, Ralph Campbell, linux-mm,
linux-kernel, kernel-janitors
On Sat, 26 Sep 2020 19:17:20 -0300 Jason Gunthorpe <jgg@ziepe.ca> wrote:
> On Sat, Sep 26, 2020 at 03:14:02PM +0300, Dan Carpenter wrote:
> > 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: 1f9c4bb986d9 ("mm/memremap_pages: convert to 'struct range'")
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> > Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
> > ---
> > v2: The first version introduced a locking bug
> > v3: Markus Elfring pointed out that the Fixes tag was wrong. This bug
> > was in the original commit and then fixed and then re-introduced. I was
> > quite bothered by how this bug lasted so long in the source code, but
> > now we know. As soon as it is introduced we fixed it.
> >
> > One problem with the kernel QC process is that I think everyone marks
> > the bug as "old/dealt with" so it was only because I was added a new
> > check for resource leaks that it was found when it was re-introduced.
> >
> > lib/test_hmm.c | 44 ++++++++++++++++++++++----------------------
> > 1 file changed, 22 insertions(+), 22 deletions(-)
>
> Hi Andrew,
>
> I don't have have any hmm related patches this cycle, can you take
> this into your tree?
>
> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Thanks.
It's actually a fix against Dan Williams' -mm patch "mm/memremap_pages:
convert to 'struct range'"
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH v3] mm/hmm/test: use after free in dmirror_allocate_chunk()
2020-09-29 0:52 ` Andrew Morton
@ 2020-09-29 1:25 ` Dan Williams
0 siblings, 0 replies; 6+ messages in thread
From: Dan Williams @ 2020-09-29 1:25 UTC (permalink / raw)
To: Andrew Morton
Cc: Jason Gunthorpe, Dan Carpenter, Jérôme Glisse,
Markus Elfring, Wei Yongjun, Ralph Campbell, Linux MM,
Linux Kernel Mailing List, kernel-janitors
On Mon, Sep 28, 2020 at 5:52 PM Andrew Morton <akpm@linux-foundation.org> wrote:
>
> On Sat, 26 Sep 2020 19:17:20 -0300 Jason Gunthorpe <jgg@ziepe.ca> wrote:
>
> > On Sat, Sep 26, 2020 at 03:14:02PM +0300, Dan Carpenter wrote:
> > > 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: 1f9c4bb986d9 ("mm/memremap_pages: convert to 'struct range'")
> > > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> > > Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
> > > ---
> > > v2: The first version introduced a locking bug
> > > v3: Markus Elfring pointed out that the Fixes tag was wrong. This bug
> > > was in the original commit and then fixed and then re-introduced. I was
> > > quite bothered by how this bug lasted so long in the source code, but
> > > now we know. As soon as it is introduced we fixed it.
> > >
> > > One problem with the kernel QC process is that I think everyone marks
> > > the bug as "old/dealt with" so it was only because I was added a new
> > > check for resource leaks that it was found when it was re-introduced.
> > >
> > > lib/test_hmm.c | 44 ++++++++++++++++++++++----------------------
> > > 1 file changed, 22 insertions(+), 22 deletions(-)
> >
> > Hi Andrew,
> >
> > I don't have have any hmm related patches this cycle, can you take
> > this into your tree?
> >
> > Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
>
> Thanks.
>
> It's actually a fix against Dan Williams' -mm patch "mm/memremap_pages:
> convert to 'struct range'"
Yes, sorry, for the fix:
Acked-by: Dan Williams <dan.j.williams@intel.com>
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2020-09-29 1:26 UTC | newest]
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2020-09-25 19:30 [PATCH v2] mm/hmm/test: use after free in dmirror_allocate_chunk() Markus Elfring
2020-09-26 12:14 ` [PATCH v3] " Dan Carpenter
2020-09-26 13:10 ` Markus Elfring
2020-09-26 22:17 ` Jason Gunthorpe
2020-09-29 0:52 ` Andrew Morton
2020-09-29 1:25 ` Dan Williams
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