* [PATCH] infiniband: fix a possible use-after-free bug
@ 2018-06-01 18:31 Cong Wang
2018-06-04 16:23 ` Gi-Oh Kim
2018-06-04 16:42 ` Jason Gunthorpe
0 siblings, 2 replies; 6+ messages in thread
From: Cong Wang @ 2018-06-01 18:31 UTC (permalink / raw)
To: linux-kernel
Cc: noamr, Cong Wang, Sean Hefty, Doug Ledford, Jason Gunthorpe, linux-rdma
ucma_process_join() will free the new allocated "mc" struct,
if there is any error after that, especially the copy_to_user().
But in parallel, ucma_leave_multicast() could find this "mc"
through idr_find() before ucma_process_join() frees it, since it
is already published.
So "mc" could be used in ucma_leave_multicast() after it is been
allocated and freed in ucma_process_join(), since we don't refcnt
it.
Fix this by separating "publish" from ID allocation, so that we
can get an ID first and publish it later after copy_to_user().
Fixes c8f6a362bf3e ("RDMA/cma: Add multicast communication support")
Reported-by: Noam Rathaus <noamr@beyondsecurity.com>
Cc: Sean Hefty <sean.hefty@intel.com>
Cc: Doug Ledford <dledford@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: linux-rdma@vger.kernel.org
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
---
drivers/infiniband/core/ucma.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
index eab43b17e9cf..ec8fb289621f 100644
--- a/drivers/infiniband/core/ucma.c
+++ b/drivers/infiniband/core/ucma.c
@@ -235,7 +235,7 @@ static struct ucma_multicast* ucma_alloc_multicast(struct ucma_context *ctx)
return NULL;
mutex_lock(&mut);
- mc->id = idr_alloc(&multicast_idr, mc, 0, 0, GFP_KERNEL);
+ mc->id = idr_alloc(&multicast_idr, NULL, 0, 0, GFP_KERNEL);
mutex_unlock(&mut);
if (mc->id < 0)
goto error;
@@ -1421,6 +1421,10 @@ static ssize_t ucma_process_join(struct ucma_file *file,
goto err3;
}
+ mutex_lock(&mut);
+ idr_replace(&multicast_idr, mc, mc->id);
+ mutex_unlock(&mut);
+
mutex_unlock(&file->mut);
ucma_put_ctx(ctx);
return 0;
--
2.13.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] infiniband: fix a possible use-after-free bug
2018-06-01 18:31 [PATCH] infiniband: fix a possible use-after-free bug Cong Wang
@ 2018-06-04 16:23 ` Gi-Oh Kim
2018-06-04 16:30 ` Cong Wang
2018-06-04 16:46 ` Jason Gunthorpe
2018-06-04 16:42 ` Jason Gunthorpe
1 sibling, 2 replies; 6+ messages in thread
From: Gi-Oh Kim @ 2018-06-04 16:23 UTC (permalink / raw)
To: Cong Wang
Cc: linux-kernel, noamr, Sean Hefty, Doug Ledford, Jason Gunthorpe,
linux-rdma
On Fri, Jun 1, 2018 at 8:31 PM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> ucma_process_join() will free the new allocated "mc" struct,
> if there is any error after that, especially the copy_to_user().
>
> But in parallel, ucma_leave_multicast() could find this "mc"
> through idr_find() before ucma_process_join() frees it, since it
> is already published.
>
> So "mc" could be used in ucma_leave_multicast() after it is been
> allocated and freed in ucma_process_join(), since we don't refcnt
> it.
>
> Fix this by separating "publish" from ID allocation, so that we
> can get an ID first and publish it later after copy_to_user().
>
> Fixes c8f6a362bf3e ("RDMA/cma: Add multicast communication support")
> Reported-by: Noam Rathaus <noamr@beyondsecurity.com>
> Cc: Sean Hefty <sean.hefty@intel.com>
> Cc: Doug Ledford <dledford@redhat.com>
> Cc: Jason Gunthorpe <jgg@ziepe.ca>
> Cc: linux-rdma@vger.kernel.org
> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
> ---
> drivers/infiniband/core/ucma.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
> index eab43b17e9cf..ec8fb289621f 100644
> --- a/drivers/infiniband/core/ucma.c
> +++ b/drivers/infiniband/core/ucma.c
> @@ -235,7 +235,7 @@ static struct ucma_multicast* ucma_alloc_multicast(struct ucma_context *ctx)
> return NULL;
>
> mutex_lock(&mut);
> - mc->id = idr_alloc(&multicast_idr, mc, 0, 0, GFP_KERNEL);
> + mc->id = idr_alloc(&multicast_idr, NULL, 0, 0, GFP_KERNEL);
> mutex_unlock(&mut);
> if (mc->id < 0)
> goto error;
> @@ -1421,6 +1421,10 @@ static ssize_t ucma_process_join(struct ucma_file *file,
> goto err3;
> }
>
> + mutex_lock(&mut);
> + idr_replace(&multicast_idr, mc, mc->id);
> + mutex_unlock(&mut);
> +
> mutex_unlock(&file->mut);
> ucma_put_ctx(ctx);
> return 0;
> --
> 2.13.0
>
Hi,
Your patch is reasonable to me.
Can I ask a question for that?
Could it be solved by asymmetric locking as following?
diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
index eab43b17e9cf..d8b256baec31 100644
--- a/drivers/infiniband/core/ucma.c
+++ b/drivers/infiniband/core/ucma.c
@@ -1493,6 +1493,7 @@ static ssize_t ucma_leave_multicast(struct
ucma_file *file,
if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
return -EFAULT;
+ mutex_lock(&mc->ctx->file->mut);
mutex_lock(&mut);
mc = idr_find(&multicast_idr, cmd.id);
if (!mc)
@@ -1507,11 +1508,11 @@ static ssize_t ucma_leave_multicast(struct
ucma_file *file,
if (IS_ERR(mc)) {
ret = PTR_ERR(mc);
+ mutex_unlock(&mc->ctx->file->mut);
goto out;
}
rdma_leave_multicast(mc->ctx->cm_id, (struct sockaddr *) &mc->addr);
- mutex_lock(&mc->ctx->file->mut);
ucma_cleanup_mc_events(mc);
list_del(&mc->list);
mutex_unlock(&mc->ctx->file->mut);
--
GIOH KIM
Linux Kernel Entwickler
ProfitBricks GmbH
Greifswalder Str. 207
D - 10405 Berlin
Tel: +49 176 2697 8962
Fax: +49 30 577 008 299
Email: gi-oh.kim@profitbricks.com
URL: https://www.profitbricks.de
Sitz der Gesellschaft: Berlin
Registergericht: Amtsgericht Charlottenburg, HRB 125506 B
Geschäftsführer: Achim Weiss, Matthias Steinberg, Christoph Steffens
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] infiniband: fix a possible use-after-free bug
2018-06-04 16:23 ` Gi-Oh Kim
@ 2018-06-04 16:30 ` Cong Wang
2018-06-04 16:46 ` Jason Gunthorpe
1 sibling, 0 replies; 6+ messages in thread
From: Cong Wang @ 2018-06-04 16:30 UTC (permalink / raw)
To: Gi-Oh Kim
Cc: LKML, Noam Rathaus, Sean Hefty, Doug Ledford, Jason Gunthorpe,
linux-rdma
On Mon, Jun 4, 2018 at 9:23 AM, Gi-Oh Kim <gi-oh.kim@profitbricks.com> wrote:
> Hi,
>
> Your patch is reasonable to me.
> Can I ask a question for that?
> Could it be solved by asymmetric locking as following?
Maybe, if you are sure taking file->mut is safe in that place.
Can you double check atomic_inc_not_zero(&mc->ctx->ref)?
I am too far away from familiar with infiniband. ;)
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] infiniband: fix a possible use-after-free bug
2018-06-01 18:31 [PATCH] infiniband: fix a possible use-after-free bug Cong Wang
2018-06-04 16:23 ` Gi-Oh Kim
@ 2018-06-04 16:42 ` Jason Gunthorpe
1 sibling, 0 replies; 6+ messages in thread
From: Jason Gunthorpe @ 2018-06-04 16:42 UTC (permalink / raw)
To: Cong Wang; +Cc: linux-kernel, noamr, Sean Hefty, Doug Ledford, linux-rdma
On Fri, Jun 01, 2018 at 11:31:44AM -0700, Cong Wang wrote:
> ucma_process_join() will free the new allocated "mc" struct,
> if there is any error after that, especially the copy_to_user().
>
> But in parallel, ucma_leave_multicast() could find this "mc"
> through idr_find() before ucma_process_join() frees it, since it
> is already published.
>
> So "mc" could be used in ucma_leave_multicast() after it is been
> allocated and freed in ucma_process_join(), since we don't refcnt
> it.
>
> Fix this by separating "publish" from ID allocation, so that we
> can get an ID first and publish it later after copy_to_user().
>
> Fixes c8f6a362bf3e ("RDMA/cma: Add multicast communication support")
> Reported-by: Noam Rathaus <noamr@beyondsecurity.com>
> Cc: Sean Hefty <sean.hefty@intel.com>
> Cc: Doug Ledford <dledford@redhat.com>
> Cc: Jason Gunthorpe <jgg@ziepe.ca>
> Cc: linux-rdma@vger.kernel.org
> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
> ---
> drivers/infiniband/core/ucma.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
Looks good to me, and we already fixed the same sort of bug in the
non-multicast IDs.. Applied to for-next
Jason
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] infiniband: fix a possible use-after-free bug
2018-06-04 16:23 ` Gi-Oh Kim
2018-06-04 16:30 ` Cong Wang
@ 2018-06-04 16:46 ` Jason Gunthorpe
2018-06-04 16:52 ` Gi-Oh Kim
1 sibling, 1 reply; 6+ messages in thread
From: Jason Gunthorpe @ 2018-06-04 16:46 UTC (permalink / raw)
To: Gi-Oh Kim
Cc: Cong Wang, linux-kernel, noamr, Sean Hefty, Doug Ledford, linux-rdma
On Mon, Jun 04, 2018 at 06:23:20PM +0200, Gi-Oh Kim wrote:
> On Fri, Jun 1, 2018 at 8:31 PM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> > ucma_process_join() will free the new allocated "mc" struct,
> > if there is any error after that, especially the copy_to_user().
> >
> > But in parallel, ucma_leave_multicast() could find this "mc"
> > through idr_find() before ucma_process_join() frees it, since it
> > is already published.
> >
> > So "mc" could be used in ucma_leave_multicast() after it is been
> > allocated and freed in ucma_process_join(), since we don't refcnt
> > it.
> >
> > Fix this by separating "publish" from ID allocation, so that we
> > can get an ID first and publish it later after copy_to_user().
> >
> > Fixes c8f6a362bf3e ("RDMA/cma: Add multicast communication support")
> > Reported-by: Noam Rathaus <noamr@beyondsecurity.com>
> > Cc: Sean Hefty <sean.hefty@intel.com>
> > Cc: Doug Ledford <dledford@redhat.com>
> > Cc: Jason Gunthorpe <jgg@ziepe.ca>
> > Cc: linux-rdma@vger.kernel.org
> > Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
> > drivers/infiniband/core/ucma.c | 6 +++++-
> > 1 file changed, 5 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
> > index eab43b17e9cf..ec8fb289621f 100644
> > +++ b/drivers/infiniband/core/ucma.c
> > @@ -235,7 +235,7 @@ static struct ucma_multicast* ucma_alloc_multicast(struct ucma_context *ctx)
> > return NULL;
> >
> > mutex_lock(&mut);
> > - mc->id = idr_alloc(&multicast_idr, mc, 0, 0, GFP_KERNEL);
> > + mc->id = idr_alloc(&multicast_idr, NULL, 0, 0, GFP_KERNEL);
> > mutex_unlock(&mut);
> > if (mc->id < 0)
> > goto error;
> > @@ -1421,6 +1421,10 @@ static ssize_t ucma_process_join(struct ucma_file *file,
> > goto err3;
> > }
> >
> > + mutex_lock(&mut);
> > + idr_replace(&multicast_idr, mc, mc->id);
> > + mutex_unlock(&mut);
> > +
> > mutex_unlock(&file->mut);
> > ucma_put_ctx(ctx);
> > return 0;
> >
>
>
> Hi,
>
> Your patch is reasonable to me.
> Can I ask a question for that?
> Could it be solved by asymmetric locking as following?
No, there are many other paths that touch multicast_idr that don't
hold both locks, we should protect all of them from accessing an
incompletely initialized structure.
Jason
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] infiniband: fix a possible use-after-free bug
2018-06-04 16:46 ` Jason Gunthorpe
@ 2018-06-04 16:52 ` Gi-Oh Kim
0 siblings, 0 replies; 6+ messages in thread
From: Gi-Oh Kim @ 2018-06-04 16:52 UTC (permalink / raw)
To: Jason Gunthorpe
Cc: Cong Wang, linux-kernel, noamr, Sean Hefty, Doug Ledford, linux-rdma
On Mon, Jun 4, 2018 at 6:46 PM, Jason Gunthorpe <jgg@ziepe.ca> wrote:
> On Mon, Jun 04, 2018 at 06:23:20PM +0200, Gi-Oh Kim wrote:
>> On Fri, Jun 1, 2018 at 8:31 PM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
>> > ucma_process_join() will free the new allocated "mc" struct,
>> > if there is any error after that, especially the copy_to_user().
>> >
>> > But in parallel, ucma_leave_multicast() could find this "mc"
>> > through idr_find() before ucma_process_join() frees it, since it
>> > is already published.
>> >
>> > So "mc" could be used in ucma_leave_multicast() after it is been
>> > allocated and freed in ucma_process_join(), since we don't refcnt
>> > it.
>> >
>> > Fix this by separating "publish" from ID allocation, so that we
>> > can get an ID first and publish it later after copy_to_user().
>> >
>> > Fixes c8f6a362bf3e ("RDMA/cma: Add multicast communication support")
>> > Reported-by: Noam Rathaus <noamr@beyondsecurity.com>
>> > Cc: Sean Hefty <sean.hefty@intel.com>
>> > Cc: Doug Ledford <dledford@redhat.com>
>> > Cc: Jason Gunthorpe <jgg@ziepe.ca>
>> > Cc: linux-rdma@vger.kernel.org
>> > Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
>> > drivers/infiniband/core/ucma.c | 6 +++++-
>> > 1 file changed, 5 insertions(+), 1 deletion(-)
>> >
>> > diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
>> > index eab43b17e9cf..ec8fb289621f 100644
>> > +++ b/drivers/infiniband/core/ucma.c
>> > @@ -235,7 +235,7 @@ static struct ucma_multicast* ucma_alloc_multicast(struct ucma_context *ctx)
>> > return NULL;
>> >
>> > mutex_lock(&mut);
>> > - mc->id = idr_alloc(&multicast_idr, mc, 0, 0, GFP_KERNEL);
>> > + mc->id = idr_alloc(&multicast_idr, NULL, 0, 0, GFP_KERNEL);
>> > mutex_unlock(&mut);
>> > if (mc->id < 0)
>> > goto error;
>> > @@ -1421,6 +1421,10 @@ static ssize_t ucma_process_join(struct ucma_file *file,
>> > goto err3;
>> > }
>> >
>> > + mutex_lock(&mut);
>> > + idr_replace(&multicast_idr, mc, mc->id);
>> > + mutex_unlock(&mut);
>> > +
>> > mutex_unlock(&file->mut);
>> > ucma_put_ctx(ctx);
>> > return 0;
>> >
>>
>>
>> Hi,
>>
>> Your patch is reasonable to me.
>> Can I ask a question for that?
>> Could it be solved by asymmetric locking as following?
>
> No, there are many other paths that touch multicast_idr that don't
> hold both locks, we should protect all of them from accessing an
> incompletely initialized structure.
>
> Jason
Understood. Thank you.
--
GIOH KIM
Linux Kernel Entwickler
ProfitBricks GmbH
Greifswalder Str. 207
D - 10405 Berlin
Tel: +49 176 2697 8962
Fax: +49 30 577 008 299
Email: gi-oh.kim@profitbricks.com
URL: https://www.profitbricks.de
Sitz der Gesellschaft: Berlin
Registergericht: Amtsgericht Charlottenburg, HRB 125506 B
Geschäftsführer: Achim Weiss, Matthias Steinberg, Christoph Steffens
^ permalink raw reply [flat|nested] 6+ messages in thread
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2018-06-01 18:31 [PATCH] infiniband: fix a possible use-after-free bug Cong Wang
2018-06-04 16:23 ` Gi-Oh Kim
2018-06-04 16:30 ` Cong Wang
2018-06-04 16:46 ` Jason Gunthorpe
2018-06-04 16:52 ` Gi-Oh Kim
2018-06-04 16:42 ` Jason Gunthorpe
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