[PATCH for-rc] RDMA/cma: fix race between addr_handler and resolve_route

[PATCH for-rc] RDMA/cma: fix race between addr_handler and resolve_route

[Håkon Bugge]

A syzkaller test hits a NULL pointer dereference in
rdma_resolve_route():

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 7185 Comm: syz-executor670 Not tainted 4.14.147 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
task: ffff8880a7c4c0c0 task.stack: ffff888084398000
RIP: 0010:rdma_cap_ib_sa include/rdma/ib_verbs.h:2682 [inline]
RIP: 0010:rdma_resolve_route+0x11f/0x2bf0 drivers/infiniband/core/cma.c:2678
RSP: 0018:ffff88808439fa20 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000029 RSI: 0000000000000001 RDI: 0000000000000148
RBP: ffff88808439fbc0 R08: ffff8880a7c4c0c0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88809f540dc0
R13: 0000000000000000 R14: 0000000000000000 R15: ffff88809f540f78
FS:  00007f03a8778700(0000) GS:ffff8880aee00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f03a8777e78 CR3: 000000008afd9000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  ucma_resolve_route+0xab/0x100 drivers/infiniband/core/ucma.c:740
  ucma_write+0x231/0x310 drivers/infiniband/core/ucma.c:1672
  __vfs_write+0x105/0x6b0 fs/read_write.c:480
  vfs_write+0x198/0x500 fs/read_write.c:544
  SYSC_write fs/read_write.c:590 [inline]
  SyS_write+0xfd/0x230 fs/read_write.c:582
  do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
  entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x446a49
RSP: 002b:00007f03a8777db8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00000000006dbc48 RCX: 0000000000446a49
RDX: 0000000000000010 RSI: 0000000020000200 RDI: 0000000000000004
RBP: 00000000006dbc40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc4c
R13: 00007ffea0dde3ef R14: 00007f03a87789c0 R15: 0000000000000000
Code: 00 48 c1 ea 03 80 3c 02 00 0f 85 ea 24 00 00 48 b8 00 00 00 00 00 fc
ff df 4d 8b 34 24 49 8d be 48 01 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00
0f 85 d1 24 00 00 48 b8 00 00 00 00 00 fc ff df 41
RIP: rdma_cap_ib_sa include/rdma/ib_verbs.h:2682 [inline] RSP:
ffff88808439fa20
RIP: rdma_resolve_route+0x11f/0x2bf0 drivers/infiniband/core/cma.c:2678
RSP: ffff88808439fa20

The crash is caused by a race between the CM state updates in
addr_handler() and rdma_resolve_route().

The syzkaller program executes following sequence:

1. rdma_create_id()
2. rdma_resolve_ip()
3. rdma_resolve_route()

Please note the lack of rdma_get_cm_event() between 2 and 3 above. The
following happens:

Thread 1                      CM_ID state                    Thread 2
rdma_create_id()                     IDLE
rdma_resolve_ip()              ADDR_QUERY
                                                       addr_handler()
                            ADDR_RESOLVED                 (set state)
rdma_resolve_route()
  (check state and set to)    ROUTE_QUERY
                                           --> cma_cm_event_handler()
                               DESTROYING             (returns error)
                                                --> rdma_destroy_id()
--> rdma_cap_ib_sa()
(but cm_id has been destroyed)

I see two solutions; a) let addr_handler() only change the state once,
to one of ADDR_RESOLVED, ADDR_BOUND, or DESTROYING or b) add mutex
locking to rdma_resolve_addr(). b) requires addr_handler() to
relinquish the lock when calling the event handler, as the event
handler typically will call rdma_resolve_route() before returning.

The b) solution is implemented herein.

Reported-by: syzbot+69226cc89d87fd4f8f40@syzkaller.appspotmail.com
Signed-off-by: Håkon Bugge <haakon.bugge@oracle.com>
Cc: stable@vger.kernel.org
---
 drivers/infiniband/core/cma.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 2dec3a02ab9f..45f26bc0fbfe 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -2979,8 +2979,11 @@ int rdma_resolve_route(struct rdma_cm_id *id, unsigned long timeout_ms)
 	int ret;
 
 	id_priv = container_of(id, struct rdma_id_private, id);
-	if (!cma_comp_exch(id_priv, RDMA_CM_ADDR_RESOLVED, RDMA_CM_ROUTE_QUERY))
+	mutex_lock(&id_priv->handler_mutex);
+	if (!cma_comp_exch(id_priv, RDMA_CM_ADDR_RESOLVED, RDMA_CM_ROUTE_QUERY)) {
+		mutex_unlock(&id_priv->handler_mutex);
 		return -EINVAL;
+	}
 
 	atomic_inc(&id_priv->refcount);
 	if (rdma_cap_ib_sa(id->device, id->port_num))
@@ -2995,9 +2998,12 @@ int rdma_resolve_route(struct rdma_cm_id *id, unsigned long timeout_ms)
 	if (ret)
 		goto err;
 
+	mutex_unlock(&id_priv->handler_mutex);
 	return 0;
 err:
 	cma_comp_exch(id_priv, RDMA_CM_ROUTE_QUERY, RDMA_CM_ADDR_RESOLVED);
+	mutex_unlock(&id_priv->handler_mutex);
+
 	cma_deref_id(id_priv);
 	return ret;
 }
@@ -3085,6 +3091,7 @@ static void addr_handler(int status, struct sockaddr *src_addr,
 	struct rdma_cm_event event = {};
 	struct sockaddr *addr;
 	struct sockaddr_storage old_addr;
+	int ret;
 
 	mutex_lock(&id_priv->handler_mutex);
 	if (!cma_comp_exch(id_priv, RDMA_CM_ADDR_QUERY,
@@ -3119,7 +3126,11 @@ static void addr_handler(int status, struct sockaddr *src_addr,
 	} else
 		event.event = RDMA_CM_EVENT_ADDR_RESOLVED;
 
-	if (cma_cm_event_handler(id_priv, &event)) {
+	mutex_unlock(&id_priv->handler_mutex);
+	ret = cma_cm_event_handler(id_priv, &event);
+	mutex_lock(&id_priv->handler_mutex);
+
+	if (ret) {
 		cma_exch(id_priv, RDMA_CM_DESTROYING);
 		mutex_unlock(&id_priv->handler_mutex);
 		rdma_destroy_id(&id_priv->id);
-- 
2.20.1

Re: [PATCH for-rc] RDMA/cma: fix race between addr_handler and resolve_route

[Jason Gunthorpe]

On Fri, Apr 03, 2020 at 08:43:28PM +0200, Håkon Bugge wrote:
> A syzkaller test hits a NULL pointer dereference in
> rdma_resolve_route():

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git for-next

This commit in 5.7 probably fixes this:

commit 7c11910783a1ea17e88777552ef146cace607b3c
Author: Jason Gunthorpe <jgg@ziepe.ca>
Date:   Tue Feb 18 15:45:38 2020 -0400

    RDMA/ucma: Put a lock around every call to the rdma_cm layer


Lets find out.

Jason

Re: [PATCH for-rc] RDMA/cma: fix race between addr_handler and resolve_route

[Håkon Bugge]

> On 3 Apr 2020, at 20:57, Jason Gunthorpe <jgg@mellanox.com> wrote:
> 
> On Fri, Apr 03, 2020 at 08:43:28PM +0200, Håkon Bugge wrote:
>> A syzkaller test hits a NULL pointer dereference in
>> rdma_resolve_route():
> 
> #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git for-next
> 
> This commit in 5.7 probably fixes this:

I think it will not. The mutex in 7c11910783a1 ("RDMA/ucma: Put a lock around every call to the rdma_cm layer") will not prevent addr_handler() to run concurrently with rdma_resolve_route(), right?

And, I also suspect 7c11910783a1 to have major performance impact. But, that's a different story.


Thxs, Håkon




> 
> commit 7c11910783a1ea17e88777552ef146cace607b3c
> Author: Jason Gunthorpe <jgg@ziepe.ca>
> Date:   Tue Feb 18 15:45:38 2020 -0400
> 
>    RDMA/ucma: Put a lock around every call to the rdma_cm layer
> 
> 
> Lets find out.
> 
> Jason

Re: [PATCH for-rc] RDMA/cma: fix race between addr_handler and resolve_route

[Jason Gunthorpe]

On Fri, Apr 03, 2020 at 09:07:10PM +0200, Håkon Bugge wrote:
> 
> 
> > On 3 Apr 2020, at 20:57, Jason Gunthorpe <jgg@mellanox.com> wrote:
> > 
> > On Fri, Apr 03, 2020 at 08:43:28PM +0200, Håkon Bugge wrote:
> >> A syzkaller test hits a NULL pointer dereference in
> >> rdma_resolve_route():
> > 
> > #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git for-next
> > 
> > This commit in 5.7 probably fixes this:
> 
> I think it will not. The mutex in 7c11910783a1 ("RDMA/ucma: Put a
> lock around every call to the rdma_cm layer") will not prevent
> addr_handler() to run concurrently with rdma_resolve_route(), right?

Hmm. Perhaps so. But your patch isn't nearly enough if that is the
case, you've only considered resolve_route, but it could run
concurrently with *anything*, with the usual problems.

Plus addr_handler calls rdma_destroy_id().. Oh wow is that ever
completely screwed up. Sigh.

Probably the simplest answer is to have ucma fail operations that are
not permitted while an async_handler is pending. I'm guessing the only
operation that would be valid is rdma_destroy_id?

> And, I also suspect 7c11910783a1 to have major performance
> impact. But, that's a different story.

*shrug* I no longer care. The work to fix this in a performant way is
enormous and nobody wants to do it. 

Until that time we are taking a 'Big Lock' approach to all concurrancy
problems with rdma_cm as this code is *completely* broken for
concurrency.

Which is why I'm not taking this patch..

Jason

Re: [PATCH for-rc] RDMA/cma: fix race between addr_handler and resolve_route

[Håkon Bugge]

> On 3 Apr 2020, at 21:36, Jason Gunthorpe <jgg@mellanox.com> wrote:
> 
> On Fri, Apr 03, 2020 at 09:07:10PM +0200, Håkon Bugge wrote:
>> 
>> 
>>> On 3 Apr 2020, at 20:57, Jason Gunthorpe <jgg@mellanox.com> wrote:
>>> 
>>> On Fri, Apr 03, 2020 at 08:43:28PM +0200, Håkon Bugge wrote:
>>>> A syzkaller test hits a NULL pointer dereference in
>>>> rdma_resolve_route():
>>> 
>>> #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git for-next
>>> 
>>> This commit in 5.7 probably fixes this:
>> 
>> I think it will not. The mutex in 7c11910783a1 ("RDMA/ucma: Put a
>> lock around every call to the rdma_cm layer") will not prevent
>> addr_handler() to run concurrently with rdma_resolve_route(), right?
> 
> Hmm. Perhaps so. But your patch isn't nearly enough if that is the
> case, you've only considered resolve_route, but it could run
> concurrently with *anything*, with the usual problems.

I was about to argue my case, but looking more into the code I tend to agree with you more and more. I thought, at least, that the rdma_foo_bar() functions had atomic checks on the state and bailed out if the state was inappropriate, but that is not the case all the time. 

And the code that transitions the state from FOO to BAR, letting others observe BAR, and then conditionally setting it back to FOO isn't exactly great...

> Plus addr_handler calls rdma_destroy_id().. Oh wow is that ever
> completely screwed up. Sigh.
> 
> Probably the simplest answer is to have ucma fail operations that are
> not permitted while an async_handler is pending. I'm guessing the only
> operation that would be valid is rdma_destroy_id?

Yes, that would take care of this class of errors, I agree. On a real systems (vs. the syzkaller setup), you may receive (almost any) CM packet ay any time, and that concurrency we must handle.

Shall I make a v2 base on next based on this idea, or do you have something coming?

>> And, I also suspect 7c11910783a1 to have major performance
>> impact. But, that's a different story.
> 
> *shrug* I no longer care. The work to fix this in a performant way is
> enormous and nobody wants to do it. 
> 
> Until that time we are taking a 'Big Lock' approach to all concurrancy
> problems with rdma_cm as this code is *completely* broken for
> concurrency.

Have you considered putting the hammer inside the cm_id instead of the context? Would that allow more concurrency and still avoid the 10ish syzkaller bugs?

> Which is why I'm not taking this patch..

At least I made a good explanation of the bug ;-)


Thxs, Håkon

Re: [PATCH for-rc] RDMA/cma: fix race between addr_handler and resolve_route

[Jason Gunthorpe]

On Mon, Apr 06, 2020 at 07:00:46PM +0200, Håkon Bugge wrote:
> 
> 
> > On 3 Apr 2020, at 21:36, Jason Gunthorpe <jgg@mellanox.com> wrote:
> > 
> > On Fri, Apr 03, 2020 at 09:07:10PM +0200, Håkon Bugge wrote:
> >> 
> >> 
> >>> On 3 Apr 2020, at 20:57, Jason Gunthorpe <jgg@mellanox.com> wrote:
> >>> 
> >>> On Fri, Apr 03, 2020 at 08:43:28PM +0200, Håkon Bugge wrote:
> >>>> A syzkaller test hits a NULL pointer dereference in
> >>>> rdma_resolve_route():
> >>> 
> >>> #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git for-next
> >>> 
> >>> This commit in 5.7 probably fixes this:
> >> 
> >> I think it will not. The mutex in 7c11910783a1 ("RDMA/ucma: Put a
> >> lock around every call to the rdma_cm layer") will not prevent
> >> addr_handler() to run concurrently with rdma_resolve_route(), right?
> > 
> > Hmm. Perhaps so. But your patch isn't nearly enough if that is the
> > case, you've only considered resolve_route, but it could run
> > concurrently with *anything*, with the usual problems.
> 
> I was about to argue my case, but looking more into the code I tend
> to agree with you more and more. I thought, at least, that the
> rdma_foo_bar() functions had atomic checks on the state and bailed
> out if the state was inappropriate, but that is not the case all the
> time.
> 
> And the code that transitions the state from FOO to BAR, letting
> others observe BAR, and then conditionally setting it back to FOO
> isn't exactly great...

Ah, I did remember it right then :)

> > Probably the simplest answer is to have ucma fail operations that are
> > not permitted while an async_handler is pending. I'm guessing the only
> > operation that would be valid is rdma_destroy_id?
>
> Yes, that would take care of this class of errors, I agree. On a
> real systems (vs. the syzkaller setup), you may receive (almost any)
> CM packet ay any time, and that concurrency we must handle.

As I understand it, a correct application has to manage the RDMA CM
state machine, so if it has launched a background resolution then it
must complete/stop that before going on to do something else?

ie this is why the kernel ULPs theoretically don't need the extra
locking in ucm?

However, I'm not sure what the state machine is supposed to look
like..

> Shall I make a v2 base on next based on this idea, or do you have
> something coming?

Sure, I have nothing :)

Also that rdma_destroy_id in addr_handler looks wrong.. ie we still
retain pointers to the rdma_cm_id it destroys inside the struct
ucma_context, don't we?

> > Until that time we are taking a 'Big Lock' approach to all concurrancy
> > problems with rdma_cm as this code is *completely* broken for
> > concurrency.
> 
> Have you considered putting the hammer inside the cm_id instead of
> the context? Would that allow more concurrency and still avoid the
> 10ish syzkaller bugs?

It is, isn't it? Here the 'struct ucma_context *' is actually
per-cm_id, confusing right?

Jason

Re: [PATCH for-rc] RDMA/cma: fix race between addr_handler and resolve_route

[Håkon Bugge]

> On 6 Apr 2020, at 19:31, Jason Gunthorpe <jgg@mellanox.com> wrote:
> 
> On Mon, Apr 06, 2020 at 07:00:46PM +0200, Håkon Bugge wrote:
>> 
>> 
>>> On 3 Apr 2020, at 21:36, Jason Gunthorpe <jgg@mellanox.com> wrote:
>>> 
>>> On Fri, Apr 03, 2020 at 09:07:10PM +0200, Håkon Bugge wrote:
>>>> 
>>>> 
>>>>> On 3 Apr 2020, at 20:57, Jason Gunthorpe <jgg@mellanox.com> wrote:
>>>>> 
>>>>> On Fri, Apr 03, 2020 at 08:43:28PM +0200, Håkon Bugge wrote:
>>>>>> A syzkaller test hits a NULL pointer dereference in
>>>>>> rdma_resolve_route():
>>>>> 
>>>>> #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git for-next
>>>>> 
>>>>> This commit in 5.7 probably fixes this:
>>>> 
>>>> I think it will not. The mutex in 7c11910783a1 ("RDMA/ucma: Put a
>>>> lock around every call to the rdma_cm layer") will not prevent
>>>> addr_handler() to run concurrently with rdma_resolve_route(), right?
>>> 
>>> Hmm. Perhaps so. But your patch isn't nearly enough if that is the
>>> case, you've only considered resolve_route, but it could run
>>> concurrently with *anything*, with the usual problems.
>> 
>> I was about to argue my case, but looking more into the code I tend
>> to agree with you more and more. I thought, at least, that the
>> rdma_foo_bar() functions had atomic checks on the state and bailed
>> out if the state was inappropriate, but that is not the case all the
>> time.
>> 
>> And the code that transitions the state from FOO to BAR, letting
>> others observe BAR, and then conditionally setting it back to FOO
>> isn't exactly great...
> 
> Ah, I did remember it right then :)
> 
>>> Probably the simplest answer is to have ucma fail operations that are
>>> not permitted while an async_handler is pending. I'm guessing the only
>>> operation that would be valid is rdma_destroy_id?
>> 
>> Yes, that would take care of this class of errors, I agree. On a
>> real systems (vs. the syzkaller setup), you may receive (almost any)
>> CM packet ay any time, and that concurrency we must handle.
> 
> As I understand it, a correct application has to manage the RDMA CM
> state machine, so if it has launched a background resolution then it
> must complete/stop that before going on to do something else?
> 
> ie this is why the kernel ULPs theoretically don't need the extra
> locking in ucm?

We expect kernel ULPs to behave as good citizens. For example, we expect them to get the ADDR_RESOLVED event _before_ calling resolve_route() (as opposed to this syzkaller repro).

> However, I'm not sure what the state machine is supposed to look
> like..

The neat state machines in Figure 13{5,6} in IBTA version 1.3. If you do not have it handy, I can send you the PDF off list.

>> Shall I make a v2 base on next based on this idea, or do you have
>> something coming?
> 
> Sure, I have nothing :)
> 
> Also that rdma_destroy_id in addr_handler looks wrong.. ie we still
> retain pointers to the rdma_cm_id it destroys inside the struct
> ucma_context, don't we?

On entry from user-space, we use the u32 id and looks it up in the XArray. But if rdma_destoy_id() is called asynchronously called between ucma_get_ctx_dev() and the de-reference of ctx->cm_id, we are toast.

>>> Until that time we are taking a 'Big Lock' approach to all concurrancy
>>> problems with rdma_cm as this code is *completely* broken for
>>> concurrency.
>> 
>> Have you considered putting the hammer inside the cm_id instead of
>> the context? Would that allow more concurrency and still avoid the
>> 10ish syzkaller bugs?
> 
> It is, isn't it? Here the 'struct ucma_context *' is actually
> per-cm_id, confusing right?

Must be, since it has a single "u32 id" ;-)


Håkon

Re: [PATCH for-rc] RDMA/cma: fix race between addr_handler and resolve_route

[Jason Gunthorpe]

On Mon, Apr 06, 2020 at 08:02:41PM +0200, Håkon Bugge wrote:

> > However, I'm not sure what the state machine is supposed to look
> > like..
> 
> The neat state machines in Figure 13{5,6} in IBTA version 1.3. If you do not have it handy, I can send you the PDF off list.

That is the IB CM state machine

The RDMA CM I thought had extra things like this defered addr_resolve
business
 
> >> Shall I make a v2 base on next based on this idea, or do you have
> >> something coming?
> > 
> > Sure, I have nothing :)
> > 
> > Also that rdma_destroy_id in addr_handler looks wrong.. ie we still
> > retain pointers to the rdma_cm_id it destroys inside the struct
> > ucma_context, don't we?
> 
> On entry from user-space, we use the u32 id and looks it up in the
> XArray. But if rdma_destoy_id() is called asynchronously called
> between ucma_get_ctx_dev() and the de-reference of ctx->cm_id, we
> are toast.

Is that what happens on the addr_handler path?

Jason

Re: [PATCH for-rc] RDMA/cma: fix race between addr_handler and resolve_route

[Håkon Bugge]

> On 6 Apr 2020, at 20:10, Jason Gunthorpe <jgg@mellanox.com> wrote:
> 
> On Mon, Apr 06, 2020 at 08:02:41PM +0200, Håkon Bugge wrote:
> 
>>> However, I'm not sure what the state machine is supposed to look
>>> like..
>> 
>> The neat state machines in Figure 13{5,6} in IBTA version 1.3. If you do not have it handy, I can send you the PDF off list.
> 
> That is the IB CM state machine
> 
> The RDMA CM I thought had extra things like this defered addr_resolve
> business

The "runway" before you can send a REQ is not captured by IBTA. So the {ADDR,ROUTE}_{QUERY,RESOLVED} states are not IBTA defined.

>>>> Shall I make a v2 base on next based on this idea, or do you have
>>>> something coming?
>>> 
>>> Sure, I have nothing :)
>>> 
>>> Also that rdma_destroy_id in addr_handler looks wrong.. ie we still
>>> retain pointers to the rdma_cm_id it destroys inside the struct
>>> ucma_context, don't we?
>> 
>> On entry from user-space, we use the u32 id and looks it up in the
>> XArray. But if rdma_destoy_id() is called asynchronously called
>> between ucma_get_ctx_dev() and the de-reference of ctx->cm_id, we
>> are toast.
> 
> Is that what happens on the addr_handler path?

No, there, the main problem is the revert of the state transitions. The first transition enables rdma_resolve_route() to pass its gate (i.e. state == ADDR_RESOLVED). Then it thinks the address is resolved, but the addr_handler changes its mind afterwards.


Thxs, Håkon

Re: [PATCH for-rc] RDMA/cma: fix race between addr_handler and resolve_route

[Jason Gunthorpe]

On Tue, Apr 14, 2020 at 12:34:35PM +0200, Håkon Bugge wrote:

> >>>> Shall I make a v2 base on next based on this idea, or do you have
> >>>> something coming?
> >>> 
> >>> Sure, I have nothing :)
> >>> 
> >>> Also that rdma_destroy_id in addr_handler looks wrong.. ie we still
> >>> retain pointers to the rdma_cm_id it destroys inside the struct
> >>> ucma_context, don't we?
> >> 
> >> On entry from user-space, we use the u32 id and looks it up in the
> >> XArray. But if rdma_destoy_id() is called asynchronously called
> >> between ucma_get_ctx_dev() and the de-reference of ctx->cm_id, we
> >> are toast.
> > 
> > Is that what happens on the addr_handler path?
> 
> No, there, the main problem is the revert of the state
> transitions. The first transition enables rdma_resolve_route() to
> pass its gate (i.e. state == ADDR_RESOLVED). Then it thinks the
> address is resolved, but the addr_handler changes its mind
> afterwards.

That is a problem, but the call to rdma_destroy_id looks like another
problem

Jason

Re: [PATCH for-rc] RDMA/cma: fix race between addr_handler and resolve_route

[Håkon Bugge]

> On 14 Apr 2020, at 14:50, Jason Gunthorpe <jgg@mellanox.com> wrote:
> 
> On Tue, Apr 14, 2020 at 12:34:35PM +0200, Håkon Bugge wrote:
> 
>>>>>> Shall I make a v2 base on next based on this idea, or do you have
>>>>>> something coming?
>>>>> 
>>>>> Sure, I have nothing :)
>>>>> 
>>>>> Also that rdma_destroy_id in addr_handler looks wrong.. ie we still
>>>>> retain pointers to the rdma_cm_id it destroys inside the struct
>>>>> ucma_context, don't we?
>>>> 
>>>> On entry from user-space, we use the u32 id and looks it up in the
>>>> XArray. But if rdma_destoy_id() is called asynchronously called
>>>> between ucma_get_ctx_dev() and the de-reference of ctx->cm_id, we
>>>> are toast.
>>> 
>>> Is that what happens on the addr_handler path?
>> 
>> No, there, the main problem is the revert of the state
>> transitions. The first transition enables rdma_resolve_route() to
>> pass its gate (i.e. state == ADDR_RESOLVED). Then it thinks the
>> address is resolved, but the addr_handler changes its mind
>> afterwards.
> 
> That is a problem, but the call to rdma_destroy_id looks like another
> problem

I am not sure. Almost all events/incoming packets, can, after the cm_id's event_handler is called from cma_ib_handler(), call rdma_destroy_id(). I assume the refcounting takes care of this.


Thxs, Håkon

Re: [PATCH for-rc] RDMA/cma: fix race between addr_handler and resolve_route

[Jason Gunthorpe]

On Tue, Apr 14, 2020 at 03:57:20PM +0200, Håkon Bugge wrote:
> 
> 
> > On 14 Apr 2020, at 14:50, Jason Gunthorpe <jgg@mellanox.com> wrote:
> > 
> > On Tue, Apr 14, 2020 at 12:34:35PM +0200, Håkon Bugge wrote:
> > 
> >>>>>> Shall I make a v2 base on next based on this idea, or do you have
> >>>>>> something coming?
> >>>>> 
> >>>>> Sure, I have nothing :)
> >>>>> 
> >>>>> Also that rdma_destroy_id in addr_handler looks wrong.. ie we still
> >>>>> retain pointers to the rdma_cm_id it destroys inside the struct
> >>>>> ucma_context, don't we?
> >>>> 
> >>>> On entry from user-space, we use the u32 id and looks it up in the
> >>>> XArray. But if rdma_destoy_id() is called asynchronously called
> >>>> between ucma_get_ctx_dev() and the de-reference of ctx->cm_id, we
> >>>> are toast.
> >>> 
> >>> Is that what happens on the addr_handler path?
> >> 
> >> No, there, the main problem is the revert of the state
> >> transitions. The first transition enables rdma_resolve_route() to
> >> pass its gate (i.e. state == ADDR_RESOLVED). Then it thinks the
> >> address is resolved, but the addr_handler changes its mind
> >> afterwards.
> > 
> > That is a problem, but the call to rdma_destroy_id looks like another
> > problem
> 
> I am not sure. Almost all events/incoming packets, can, after the
> cm_id's event_handler is called from cma_ib_handler(), call
> rdma_destroy_id(). 

I think the trick is that ucma_event_handler never returns failure
unless RDMA_CM_EVENT_CONNECT_REQUEST, which means the cm_id isn't in
the xarray yet?

> I assume the refcounting takes care of this.

There is no refcounting for destroy, it must be called once.

Jason

Re: [PATCH for-rc] RDMA/cma: fix race between addr_handler and resolve_route

[Håkon Bugge]

> On 14 Apr 2020, at 18:11, Jason Gunthorpe <jgg@mellanox.com> wrote:
> 
> On Tue, Apr 14, 2020 at 03:57:20PM +0200, Håkon Bugge wrote:
>> 
>> 
>>> On 14 Apr 2020, at 14:50, Jason Gunthorpe <jgg@mellanox.com> wrote:
>>> 
>>> On Tue, Apr 14, 2020 at 12:34:35PM +0200, Håkon Bugge wrote:
>>> 
>>>>>>>> Shall I make a v2 base on next based on this idea, or do you have
>>>>>>>> something coming?
>>>>>>> 
>>>>>>> Sure, I have nothing :)
>>>>>>> 
>>>>>>> Also that rdma_destroy_id in addr_handler looks wrong.. ie we still
>>>>>>> retain pointers to the rdma_cm_id it destroys inside the struct
>>>>>>> ucma_context, don't we?
>>>>>> 
>>>>>> On entry from user-space, we use the u32 id and looks it up in the
>>>>>> XArray. But if rdma_destoy_id() is called asynchronously called
>>>>>> between ucma_get_ctx_dev() and the de-reference of ctx->cm_id, we
>>>>>> are toast.
>>>>> 
>>>>> Is that what happens on the addr_handler path?
>>>> 
>>>> No, there, the main problem is the revert of the state
>>>> transitions. The first transition enables rdma_resolve_route() to
>>>> pass its gate (i.e. state == ADDR_RESOLVED). Then it thinks the
>>>> address is resolved, but the addr_handler changes its mind
>>>> afterwards.
>>> 
>>> That is a problem, but the call to rdma_destroy_id looks like another
>>> problem
>> 
>> I am not sure. Almost all events/incoming packets, can, after the
>> cm_id's event_handler is called from cma_ib_handler(), call
>> rdma_destroy_id(). 
> 
> I think the trick is that ucma_event_handler never returns failure
> unless RDMA_CM_EVENT_CONNECT_REQUEST, which means the cm_id isn't in
> the xarray yet?

Sure does. 1 or -ENOMEM. But the ULP's event handlers isn't that polite. But a different issue from this syzkaller one.

>> I assume the refcounting takes care of this.
> 
> There is no refcounting for destroy, it must be called once.

I was thinking about the "cma_deref_id(id_priv);" stuff, but I may have misunderstood.



Thxs, Håkon

Re: [PATCH for-rc] RDMA/cma: fix race between addr_handler and resolve_route

[Jason Gunthorpe]

On Thu, Apr 16, 2020 at 03:33:28PM +0200, Håkon Bugge wrote:

> > I think the trick is that ucma_event_handler never returns failure
> > unless RDMA_CM_EVENT_CONNECT_REQUEST, which means the cm_id isn't in
> > the xarray yet?
> 
> Sure does. 1 or -ENOMEM. But the ULP's event handlers isn't that
> polite. But a different issue from this syzkaller one.

Seems like a crazy and difficult API to me..
 
> >> I assume the refcounting takes care of this.
> > 
> > There is no refcounting for destroy, it must be called once.
> 
> I was thinking about the "cma_deref_id(id_priv);" stuff, but I may have misunderstood.

This just causes destroy_id to pause while a ref is held, there can
still be only one call to destroy_id

Jason

Re: general protection fault in rdma_resolve_route

[syzbot]

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

00-0xbfffffff] -> [mem 0x00000000-0xbfffffff]
[    0.058488] NUMA: Node 0 [mem 0x00000000-0xbfffffff] + [mem 0x100000000-0x23fffffff] -> [mem 0x00000000-0x23fffffff]
[    0.060840] NODE_DATA(0) allocated [mem 0x23fffa000-0x23fffdfff]
[    0.103932] Zone ranges:
[    0.105131]   DMA      [mem 0x0000000000001000-0x0000000000ffffff]
[    0.107499]   DMA32    [mem 0x0000000001000000-0x00000000ffffffff]
[    0.109481]   Normal   [mem 0x0000000100000000-0x000000023fffffff]
[    0.112322] Movable zone start for each node
[    0.113517] Early memory node ranges
[    0.114833]   node   0: [mem 0x0000000000001000-0x000000000009efff]
[    0.116844]   node   0: [mem 0x0000000000100000-0x00000000bfffcfff]
[    0.117754]   node   0: [mem 0x0000000100000000-0x000000023fffffff]
[    0.119114] Zeroed struct page in unavailable ranges: 101 pages
[    0.119121] Initmem setup node 0 [mem 0x0000000000001000-0x000000023fffffff]
[    0.488208] kasan: KernelAddressSanitizer initialized
[    0.491077] ACPI: PM-Timer IO Port: 0xb008
[    0.492273] ACPI: LAPIC_NMI (acpi_id[0xff] dfl dfl lint[0x1])
[    0.493758] IOAPIC[0]: apic_id 0, version 17, address 0xfec00000, GSI 0-23
[    0.496178] ACPI: INT_SRC_OVR (bus 0 bus_irq 5 global_irq 5 high level)
[    0.498589] ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 9 high level)
[    0.499528] ACPI: INT_SRC_OVR (bus 0 bus_irq 10 global_irq 10 high level)
[    0.501455] ACPI: INT_SRC_OVR (bus 0 bus_irq 11 global_irq 11 high level)
[    0.505310] Using ACPI (MADT) for SMP configuration information
[    0.507171] smpboot: Allowing 2 CPUs, 0 hotplug CPUs
[    0.508243] PM: hibernation: Registered nosave memory: [mem 0x00000000-0x00000fff]
[    0.509621] PM: hibernation: Registered nosave memory: [mem 0x0009f000-0x0009ffff]
[    0.510867] PM: hibernation: Registered nosave memory: [mem 0x000a0000-0x000effff]
[    0.511960] PM: hibernation: Registered nosave memory: [mem 0x000f0000-0x000fffff]
[    0.513141] PM: hibernation: Registered nosave memory: [mem 0xbfffd000-0xbfffffff]
[    0.514253] PM: hibernation: Registered nosave memory: [mem 0xc0000000-0xfffbbfff]
[    0.515989] PM: hibernation: Registered nosave memory: [mem 0xfffbc000-0xffffffff]
[    0.517624] [mem 0xc0000000-0xfffbbfff] available for PCI devices
[    0.518566] Booting paravirtualized kernel on KVM
[    0.519719] clocksource: refined-jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
[    0.521833] setup_percpu: NR_CPUS:64 nr_cpumask_bits:64 nr_cpu_ids:2 nr_node_ids:1
[    0.523803] percpu: Embedded 65 pages/cpu s228040 r8192 d30008 u1048576
[    0.525712] kvm-guest: stealtime: cpu 0, msr 1f6820300
[    0.526590] kvm-guest: PV spinlocks enabled
[    0.527219] PV qspinlock hash table entries: 256 (order: 0, 4096 bytes, linear)
[    0.528285] Built 1 zonelists, mobility grouping on.  Total pages: 2064262
[    0.529218] Policy zone: Normal
[    0.530013] Kernel command line: BOOT_IMAGE=/vmlinuz root=/dev/sda1 console=ttyS0 earlyprintk=serial vsyscall=native net.ifnames=0 sysctl.kernel.hung_task_all_cpu_backtrace=1
[    0.535469] Dentry cache hash table entries: 1048576 (order: 11, 8388608 bytes, linear)
[    0.538483] Inode-cache hash table entries: 524288 (order: 10, 4194304 bytes, linear)
[    0.540453] mem auto-init: stack:off, heap alloc:off, heap free:off
[    1.404586] Memory: 6936940K/8388204K available (104477K kernel code, 16962K rwdata, 19800K rodata, 2716K init, 14576K bss, 1451008K reserved, 0K cma-reserved)
[    1.409491] Running RCU self tests
[    1.410244] rcu: Preemptible hierarchical RCU implementation.
[    1.411041] rcu: 	RCU lockdep checking is enabled.
[    1.411868] rcu: 	RCU restricting CPUs from NR_CPUS=64 to nr_cpu_ids=2.
[    1.413172] rcu: 	RCU callback double-/use-after-free debug enabled.
[    1.414100] 	Trampoline variant of Tasks RCU enabled.
[    1.414856] 	Tracing variant of Tasks RCU enabled.
[    1.415720] rcu: RCU calculated value of scheduler-enlistment delay is 10 jiffies.
[    1.416920] rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=2
[    1.434818] NR_IRQS: 4352, nr_irqs: 440, preallocated irqs: 16
[    1.436389] random: get_random_bytes called from start_kernel+0x248/0x452 with crng_init=0
[    1.438577] Console: colour VGA+ 80x25
[    1.440431] printk: console [ttyS0] enabled
[    1.440431] printk: console [ttyS0] enabled
[    1.442758] printk: bootconsole [earlyser0] disabled
[    1.442758] printk: bootconsole [earlyser0] disabled
[    1.445364] Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar
[    1.446561] ... MAX_LOCKDEP_SUBCLASSES:  8
[    1.447268] ... MAX_LOCK_DEPTH:          48
[    1.448234] ... MAX_LOCKDEP_KEYS:        8192
[    1.449368] ... CLASSHASH_SIZE:          4096
[    1.450383] ... MAX_LOCKDEP_ENTRIES:     32768
[    1.451040] ... MAX_LOCKDEP_CHAINS:      65536
[    1.451749] ... CHAINHASH_SIZE:          32768
[    1.452760]  memory used by lock dependency info: 6365 kB
[    1.453563]  memory used for stack traces: 4224 kB
[    1.454931]  per task-struct memory footprint: 1920 bytes
[    1.456060] ACPI: Core revision 20210105
[    1.457395] APIC: Switch to symmetric I/O mode setup
[    1.459143] x2apic enabled
[    1.463697] Switched APIC routing to physical x2apic.
[    1.471104] ..TIMER: vector=0x30 apic1=0 pin1=0 apic2=-1 pin2=-1
[    1.472880] clocksource: tsc-early: mask: 0xffffffffffffffff max_cycles: 0x212733415c7, max_idle_ns: 440795236380 ns
[    1.474596] Calibrating delay loop (skipped) preset value.. 4599.99 BogoMIPS (lpj=22999980)
[    1.475862] pid_max: default: 32768 minimum: 301
[    1.477131] LSM: Security Framework initializing
[    1.484641] Yama: becoming mindful.
[    1.485728] AppArmor: AppArmor initialized
[    1.486377] TOMOYO Linux initialized
[    1.487338] Mount-cache hash table entries: 16384 (order: 5, 131072 bytes, linear)
[    1.488572] Mountpoint-cache hash table entries: 16384 (order: 5, 131072 bytes, linear)
[    1.492797] Last level iTLB entries: 4KB 1024, 2MB 1024, 4MB 1024
[    1.493825] Last level dTLB entries: 4KB 1024, 2MB 1024, 4MB 1024, 1GB 4
[    1.494613] Spectre V1 : Mitigation: usercopy/swapgs barriers and __user pointer sanitization
[    1.496256] Spectre V2 : Spectre mitigation: kernel not compiled with retpoline; no mitigation available!
[    1.496268] Speculative Store Bypass: Mitigation: Speculative Store Bypass disabled via prctl and seccomp
[    1.499114] MDS: Mitigation: Clear CPU buffers
[    1.500421] Freeing SMP alternatives memory: 96K
[    1.625192] smpboot: CPU0: Intel(R) Xeon(R) CPU @ 2.30GHz (family: 0x6, model: 0x3f, stepping: 0x0)
[    1.628822] Running RCU-tasks wait API self tests
[    1.734790] Performance Events: unsupported p6 CPU model 63 no PMU driver, software events only.
[    1.737061] rcu: Hierarchical SRCU implementation.
[    1.738746] NMI watchdog: Perf NMI watchdog permanently disabled
[    1.740308] smp: Bringing up secondary CPUs ...
[    1.743161] x86: Booting SMP configuration:
[    1.744082] .... node  #0, CPUs:      #1
[    0.048290] kvm-clock: cpu 1, msr 9ff4041, secondary cpu clock
[    1.746880] kvm-guest: stealtime: cpu 1, msr 1f6920300
[    1.746880] MDS CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/mds.html for more details.
[    1.746893] smp: Brought up 1 node, 2 CPUs
[    1.747731] smpboot: Max logical packages: 1
[    1.748615] smpboot: Total of 2 processors activated (9199.99 BogoMIPS)
[    1.756137] devtmpfs: initialized
[    1.766996] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
[    1.767107] kworker/u4:0 (25) used greatest stack depth: 27696 bytes left
[    1.768357] futex hash table entries: 512 (order: 4, 65536 bytes, linear)
[    1.774706] Callback from call_rcu_tasks_trace() invoked.
[    1.776981] PM: RTC time: 05:54:04, date: 2021-04-28
[    1.779484] NET: Registered protocol family 16
[    1.782350] audit: initializing netlink subsys (disabled)
[    1.789010] thermal_sys: Registered thermal governor 'step_wise'
[    1.789025] thermal_sys: Registered thermal governor 'user_space'
[    1.792224] audit: type=2000 audit(1619589244.902:1): state=initialized audit_enabled=0 res=1
[    1.793888] cpuidle: using governor menu
[    1.795710] ACPI: bus type PCI registered
[    1.797887] dca service started, version 1.12.1
[    1.799280] PCI: Using configuration type 1 for base access
[    1.834628] kworker/u4:1 (80) used greatest stack depth: 27664 bytes left
[    1.954755] kworker/u4:0 (374) used greatest stack depth: 27048 bytes left
[    2.309454] HugeTLB registered 1.00 GiB page size, pre-allocated 0 pages
[    2.314763] HugeTLB registered 2.00 MiB page size, pre-allocated 0 pages
[    2.325575] cryptd: max_cpu_qlen set to 1000
[    2.345279] Callback from call_rcu_tasks() invoked.
[    2.524609] raid6: avx2x4   gen() 15219 MB/s
[    2.694788] raid6: avx2x4   xor()  7262 MB/s
[    2.864594] raid6: avx2x2   gen() 11255 MB/s
[    3.034606] raid6: avx2x2   xor()  5120 MB/s
[    3.202375] raid6: avx2x1   gen()  6250 MB/s
[    3.372377] raid6: avx2x1   xor()  3156 MB/s
[    3.542374] raid6: sse2x4   gen()  6546 MB/s
[    3.714623] raid6: sse2x4   xor()  3857 MB/s
[    3.884599] raid6: sse2x2   gen()  5919 MB/s
[    4.054587] raid6: sse2x2   xor()  2612 MB/s
[    4.224587] raid6: sse2x1   gen()  3308 MB/s
[    4.394590] raid6: sse2x1   xor()  1499 MB/s
[    4.395909] raid6: using algorithm avx2x4 gen() 15219 MB/s
[    4.397145] raid6: .... xor() 7262 MB/s, rmw enabled
[    4.398231] raid6: using avx2x2 recovery algorithm
[    4.400027] ACPI: Added _OSI(Module Device)
[    4.401320] ACPI: Added _OSI(Processor Device)
[    4.402230] ACPI: Added _OSI(3.0 _SCP Extensions)
[    4.403371] ACPI: Added _OSI(Processor Aggregator Device)
[    4.404341] ACPI: Added _OSI(Linux-Dell-Video)
[    4.404601] ACPI: Added _OSI(Linux-Lenovo-NV-HDMI-Audio)
[    4.405681] ACPI: Added _OSI(Linux-HPI-Hybrid-Graphics)
[    4.443090] ACPI: 2 ACPI AML tables successfully acquired and loaded
[    4.483327] ACPI: Interpreter enabled
[    4.484827] ACPI: (supports S0 S3 S4 S5)
[    4.485492] ACPI: Using IOAPIC for interrupt routing
[    4.487197] PCI: Using host bridge windows from ACPI; if necessary, use "pci=nocrs" and report a bug
[    4.490999] ACPI: Enabled 16 GPEs in block 00 to 0F
[    4.570375] ACPI: PCI Root Bridge [PCI0] (domain 0000 [bus 00-ff])
[    4.571871] acpi PNP0A03:00: _OSC: OS supports [ASPM ClockPM Segments MSI HPX-Type3]
[    4.573808] acpi PNP0A03:00: fail to add MMCONFIG information, can't access extended PCI configuration space under this bridge.
[    4.578475] PCI host bridge to bus 0000:00
[    4.579556] pci_bus 0000:00: root bus resource [io  0x0000-0x0cf7 window]
[    4.581578] pci_bus 0000:00: root bus resource [io  0x0d00-0xffff window]
[    4.582582] pci_bus 0000:00: root bus resource [mem 0x000a0000-0x000bffff window]
[    4.584602] pci_bus 0000:00: root bus resource [mem 0xc0000000-0xfebfefff window]
[    4.585897] pci_bus 0000:00: root bus resource [bus 00-ff]
[    4.586983] pci 0000:00:00.0: [8086:1237] type 00 class 0x060000
[    4.596270] pci 0000:00:01.0: [8086:7110] type 00 class 0x060100
[    4.635352] pci 0000:00:01.3: [8086:7113] type 00 class 0x068000
[    4.663128] pci 0000:00:01.3: quirk: [io  0xb000-0xb03f] claimed by PIIX4 ACPI
[    4.667290] pci 0000:00:03.0: [1af4:1004] type 00 class 0x000000
[    4.681139] pci 0000:00:03.0: reg 0x10: [io  0xc000-0xc03f]
[    4.689913] pci 0000:00:03.0: reg 0x14: [mem 0xfe800000-0xfe80007f]
[    4.715281] pci 0000:00:04.0: [1af4:1000] type 00 class 0x020000
[    4.724631] pci 0000:00:04.0: reg 0x10: [io  0xc040-0xc07f]
[    4.732306] pci 0000:00:04.0: reg 0x14: [mem 0xfe801000-0xfe80107f]
[    4.755983] pci 0000:00:05.0: [1ae0:a002] type 00 class 0x030000
[    4.768756] pci 0000:00:05.0: reg 0x10: [mem 0xfe000000-0xfe7fffff]
[    4.804905] pci 0000:00:06.0: [1af4:1002] type 00 class 0x00ff00
[    4.814599] pci 0000:00:06.0: reg 0x10: [io  0xc080-0xc09f]
[    4.845385] pci 0000:00:07.0: [1af4:1005] type 00 class 0x00ff00
[    4.854677] pci 0000:00:07.0: reg 0x10: [io  0xc0a0-0xc0bf]
[    4.862019] pci 0000:00:07.0: reg 0x14: [mem 0xfe802000-0xfe80203f]
[    4.895345] ACPI: PCI Interrupt Link [LNKA] (IRQs 5 *10 11)
[    4.900887] ACPI: PCI Interrupt Link [LNKB] (IRQs 5 *10 11)
[    4.905638] ACPI: PCI Interrupt Link [LNKC] (IRQs 5 10 *11)
[    4.910451] ACPI: PCI Interrupt Link [LNKD] (IRQs 5 10 *11)
[    4.914692] ACPI: PCI Interrupt Link [LNKS] (IRQs *9)
[    4.926383] iommu: Default domain type: Translated 
[    4.928005] pci 0000:00:05.0: vgaarb: setting as boot VGA device
[    4.928005] pci 0000:00:05.0: vgaarb: VGA device added: decodes=io+mem,owns=io+mem,locks=none
[    4.928031] pci 0000:00:05.0: vgaarb: bridge control possible
[    4.929711] vgaarb: loaded
[    4.935676] SCSI subsystem initialized
[    4.938811] ACPI: bus type USB registered
[    4.940933] usbcore: registered new interface driver usbfs
[    4.944914] usbcore: registered new interface driver hub
[    4.946468] usbcore: registered new device driver usb
[    4.951257] mc: Linux media interface: v0.10
[    4.952541] videodev: Linux video capture interface: v2.00
[    4.957213] pps_core: LinuxPPS API ver. 1 registered
[    4.958276] pps_core: Software ver. 5.3.6 - Copyright 2005-2007 Rodolfo Giometti <giometti@linux.it>
[    4.963112] PTP clock support registered
[    4.966465] EDAC MC: Ver: 3.0.0
[    4.968630] Advanced Linux Sound Architecture Driver Initialized.
[    4.976928] Bluetooth: Core ver 2.22
[    4.979044] NET: Registered protocol family 31
[    4.980769] Bluetooth: HCI device and connection manager initialized
[    4.982902] Bluetooth: HCI socket layer initialized
[    4.984625] Bluetooth: L2CAP socket layer initialized
[    4.986482] Bluetooth: SCO socket layer initialized
[    4.988517] NET: Registered protocol family 8
[    4.990235] NET: Registered protocol family 20
[    4.992391] NetLabel: Initializing
[    4.994618] NetLabel:  domain hash size = 128
[    4.996509] NetLabel:  protocols = UNLABELED CIPSOv4 CALIPSO
[    4.998942] NetLabel:  unlabeled traffic allowed by default
[    5.001549] nfc: nfc_init: NFC Core ver 0.1
[    5.001549] NET: Registered protocol family 39
[    5.001549] PCI: Using ACPI for IRQ routing
[    5.005939] clocksource: Switched to clocksource kvm-clock
[    5.331782] VFS: Disk quotas dquot_6.6.0
[    5.334522] VFS: Dquot-cache hash table entries: 512 (order 0, 4096 bytes)
[    5.337855] FS-Cache: Loaded
[    5.340293] CacheFiles: Loaded
[    5.342072] TOMOYO: 2.6.0
[    5.343045] Profile 0 (used by '<kernel>') is not defined.
[    5.345255] Userland tools for TOMOYO 2.6 must be installed and policy must be initialized.
[    5.348577] Please see https://tomoyo.osdn.jp/2.6/ for more information.
[    5.351443] Kernel panic - not syncing: STOP!
[    5.353059] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.12.0-rc2-syzkaller #0
[    5.355230] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
[    5.355230] Call Trace:
[    5.355230]  dump_stack+0x156/0x1a5
[    5.355230]  panic+0x2ea/0x687
[    5.355230]  ? __warn_printk+0xf3/0xf3
[    5.355230]  ? lock_release+0x47c/0x970
[    5.355230]  ? lock_downgrade+0x8a0/0x8a0
[    5.355230]  ? vprintk_func+0x76/0x180
[    5.355230]  tomoyo_check_profile.cold+0xc9/0xe9
[    5.355230]  tomoyo_load_builtin_policy+0x27b/0x2c2
[    5.355230]  ? smack_nf_ip_init+0x77/0x77
[    5.355230]  ? tomoyo_write_domain2+0x1b0/0x1b0
[    5.355230]  ? securityfs_create_dentry+0x13a/0x530
[    5.355230]  tomoyo_initerface_init+0x1b7/0x1c2
[    5.355230]  ? tomoyo_mm_init+0x257/0x257
[    5.355230]  do_one_initcall+0xef/0x640
[    5.355230]  ? perf_trace_initcall_level+0x3d0/0x3d0
[    5.355230]  ? __this_cpu_preempt_check+0x1d/0x30
[    5.355230]  ? lock_is_held_type+0x100/0x140
[    5.355230]  kernel_init_freeable+0x58a/0x5f9
[    5.355230]  ? rest_init+0x2e4/0x2e4
[    5.355230]  kernel_init+0x12/0x16c
[    5.355230]  ret_from_fork+0x1f/0x30
[    5.355230] Rebooting in 86400 seconds..


Error text is too large and was truncated, full error text is at:
https://syzkaller.appspot.com/x/error.txt?x=17af81e1d00000


Tested on:

commit:         6cc9e215 RDMA/nldev: Add copy-on-fork attribute to get sys..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git for-next
kernel config:  https://syzkaller.appspot.com/x/.config?x=d845af22fa44b27a
dashboard link: https://syzkaller.appspot.com/bug?extid=69226cc89d87fd4f8f40
compiler: