diff mbox

[v2] general protection fault in sock_has_perm

Message ID 20180201153708.63506-1-salyzyn@android.com (mailing list archive)
State New, archived
Headers show

Commit Message

Mark Salyzyn Feb. 1, 2018, 3:37 p.m. UTC
In the absence of commit a4298e4522d6 ("net: add SOCK_RCU_FREE socket
flag") and all the associated infrastructure changes to take advantage
of a RCU grace period before freeing, there is a heightened
possibility that a security check is performed while an ill-timed
setsockopt call races in from user space.  It then is prudent to null
check sk_security, and if the case, reject the permissions.

Because of the nature of this problem, hard to duplicate, no clear
path, this patch is a simplified band-aid for stable trees lacking the
infrastructure for the series of commits leading up to providing a
suitable RCU grace period.  This adjustment is orthogonal to
infrastructure improvements that may nullify the needed check, but
could be added as good code hygiene in all trees.

general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 14233 Comm: syz-executor2 Not tainted 4.4.112-g5f6325b #28
task: ffff8801d1095f00 task.stack: ffff8800b5950000
RIP: 0010:[<ffffffff81b69b7e>]  [<ffffffff81b69b7e>] sock_has_perm+0x1fe/0x3e0 security/selinux/hooks.c:4069
RSP: 0018:ffff8800b5957ce0  EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 1ffff10016b2af9f RCX: ffffffff81b69b51
RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000010
RBP: ffff8800b5957de0 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000000 R11: 1ffff10016b2af68 R12: ffff8800b5957db8
R13: 0000000000000000 R14: ffff8800b7259f40 R15: 00000000000000d7
FS:  00007f72f5ae2700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000a2fa38 CR3: 00000001d7980000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff81b69a1f ffff8800b5957d58 00008000b5957d30 0000000041b58ab3
 ffffffff83fc82f2 ffffffff81b69980 0000000000000246 ffff8801d1096770
 ffff8801d3165668 ffffffff8157844b ffff8801d1095f00
 ffff880000000001
Call Trace:
[<ffffffff81b6a19d>] selinux_socket_setsockopt+0x4d/0x80 security/selinux/hooks.c:4338
[<ffffffff81b4873d>] security_socket_setsockopt+0x7d/0xb0 security/security.c:1257
[<ffffffff82df1ac8>] SYSC_setsockopt net/socket.c:1757 [inline]
[<ffffffff82df1ac8>] SyS_setsockopt+0xe8/0x250 net/socket.c:1746
[<ffffffff83776499>] entry_SYSCALL_64_fastpath+0x16/0x92
Code: c2 42 9b b6 81 be 01 00 00 00 48 c7 c7 a0 cb 2b 84 e8
f7 2f 6d ff 49 8d 7d 10 48 b8 00 00 00 00 00 fc ff df 48 89
fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 83 01 00
00 41 8b 75 10 31
RIP  [<ffffffff81b69b7e>] sock_has_perm+0x1fe/0x3e0 security/selinux/hooks.c:4069
RSP <ffff8800b5957ce0>
---[ end trace 7b5aaf788fef6174 ]---

Signed-off-by: Mark Salyzyn <salyzyn@android.com>
Signed-off-by: Paul Moore <paul@linuxfoundation.org>
Signed-off-by: Greg KH <gregkh@linuxfoundation.org>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: selinux@tycho.nsa.gov
Cc: linux-security-module@vger.kernel.org
Cc: Eric Paris <eparis@parisplace.org>
Cc: Serge E. Hallyn <serge@hallyn.com>
Cc: stable <stable@vger.kernel.org> # 3.18, 4.4
Cc: linux-kernel@vger.kernel.org
---
v2: return -EFAULT for null sk_security instead of 0

 security/selinux/hooks.c | 2 ++
 1 file changed, 2 insertions(+)

Comments

Paul Moore Feb. 1, 2018, 4 p.m. UTC | #1
On Thu, Feb 1, 2018 at 10:37 AM, Mark Salyzyn <salyzyn@android.com> wrote:
> In the absence of commit a4298e4522d6 ("net: add SOCK_RCU_FREE socket
> flag") and all the associated infrastructure changes to take advantage
> of a RCU grace period before freeing, there is a heightened
> possibility that a security check is performed while an ill-timed
> setsockopt call races in from user space.  It then is prudent to null
> check sk_security, and if the case, reject the permissions.
>
> Because of the nature of this problem, hard to duplicate, no clear
> path, this patch is a simplified band-aid for stable trees lacking the
> infrastructure for the series of commits leading up to providing a
> suitable RCU grace period.  This adjustment is orthogonal to
> infrastructure improvements that may nullify the needed check, but
> could be added as good code hygiene in all trees.
>
> general protection fault: 0000 [#1] PREEMPT SMP KASAN
> CPU: 1 PID: 14233 Comm: syz-executor2 Not tainted 4.4.112-g5f6325b #28
> task: ffff8801d1095f00 task.stack: ffff8800b5950000
> RIP: 0010:[<ffffffff81b69b7e>]  [<ffffffff81b69b7e>] sock_has_perm+0x1fe/0x3e0 security/selinux/hooks.c:4069
> RSP: 0018:ffff8800b5957ce0  EFLAGS: 00010202
> RAX: dffffc0000000000 RBX: 1ffff10016b2af9f RCX: ffffffff81b69b51
> RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000010
> RBP: ffff8800b5957de0 R08: 0000000000000001 R09: 0000000000000001
> R10: 0000000000000000 R11: 1ffff10016b2af68 R12: ffff8800b5957db8
> R13: 0000000000000000 R14: ffff8800b7259f40 R15: 00000000000000d7
> FS:  00007f72f5ae2700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000a2fa38 CR3: 00000001d7980000 CR4: 0000000000160670
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Stack:
>  ffffffff81b69a1f ffff8800b5957d58 00008000b5957d30 0000000041b58ab3
>  ffffffff83fc82f2 ffffffff81b69980 0000000000000246 ffff8801d1096770
>  ffff8801d3165668 ffffffff8157844b ffff8801d1095f00
>  ffff880000000001
> Call Trace:
> [<ffffffff81b6a19d>] selinux_socket_setsockopt+0x4d/0x80 security/selinux/hooks.c:4338
> [<ffffffff81b4873d>] security_socket_setsockopt+0x7d/0xb0 security/security.c:1257
> [<ffffffff82df1ac8>] SYSC_setsockopt net/socket.c:1757 [inline]
> [<ffffffff82df1ac8>] SyS_setsockopt+0xe8/0x250 net/socket.c:1746
> [<ffffffff83776499>] entry_SYSCALL_64_fastpath+0x16/0x92
> Code: c2 42 9b b6 81 be 01 00 00 00 48 c7 c7 a0 cb 2b 84 e8
> f7 2f 6d ff 49 8d 7d 10 48 b8 00 00 00 00 00 fc ff df 48 89
> fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 83 01 00
> 00 41 8b 75 10 31
> RIP  [<ffffffff81b69b7e>] sock_has_perm+0x1fe/0x3e0 security/selinux/hooks.c:4069
> RSP <ffff8800b5957ce0>
> ---[ end trace 7b5aaf788fef6174 ]---
>
> Signed-off-by: Mark Salyzyn <salyzyn@android.com>
> Signed-off-by: Paul Moore <paul@linuxfoundation.org>

No, in the previous thread I gave my ack, not my sign-off; please be
more careful in the future.  It may seem silly, especially in this
particular case, but it is an important distinction when things like
the DCO are concerned.

Anyway, here is my ack again.

Acked-by: Paul Moore <paul@paul-moore.com>

> Signed-off-by: Greg KH <gregkh@linuxfoundation.org>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Stephen Smalley <sds@tycho.nsa.gov>
> Cc: selinux@tycho.nsa.gov
> Cc: linux-security-module@vger.kernel.org
> Cc: Eric Paris <eparis@parisplace.org>
> Cc: Serge E. Hallyn <serge@hallyn.com>
> Cc: stable <stable@vger.kernel.org> # 3.18, 4.4
> Cc: linux-kernel@vger.kernel.org
> ---
> v2: return -EFAULT for null sk_security instead of 0
>
>  security/selinux/hooks.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index 8644d864e3c1..795efa71d656 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -4342,6 +4342,8 @@ static int sock_has_perm(struct sock *sk, u32 perms)
>         struct common_audit_data ad;
>         struct lsm_network_audit net = {0,};
>
> +       if (!sksec)
> +               return -EFAULT;
>         if (sksec->sid == SECINITSID_KERNEL)
>                 return 0;
>
> --
> 2.16.0.rc1.238.g530d649a79-goog
Mark Salyzyn Feb. 1, 2018, 4:20 p.m. UTC | #2
On 02/01/2018 08:00 AM, Paul Moore wrote:
> On Thu, Feb 1, 2018 at 10:37 AM, Mark Salyzyn <salyzyn@android.com> wrote:
>> In the absence of commit a4298e4522d6 ("net: add SOCK_RCU_FREE socket
>> flag") and all the associated infrastructure changes to take advantage
>> of a RCU grace period before freeing, there is a heightened
>> possibility that a security check is performed while an ill-timed
>> setsockopt call races in from user space.  It then is prudent to null
>> check sk_security, and if the case, reject the permissions.
>>
>> . . .
>> ---[ end trace 7b5aaf788fef6174 ]---
>>
>> Signed-off-by: Mark Salyzyn <salyzyn@android.com>
>> Signed-off-by: Paul Moore <paul@linuxfoundation.org>
> No, in the previous thread I gave my ack, not my sign-off; please be
> more careful in the future.  It may seem silly, especially in this
> particular case, but it is an important distinction when things like
> the DCO are concerned.
>
> Anyway, here is my ack again.
>
> Acked-by: Paul Moore <paul@paul-moore.com>
>
Ok, both Greg KH and yours should be considered Acked-By. Been 
overstepping this boundary for _years_. AFAIK Signed-off-by is still 
pending from Stephen Smalley <sds@tycho.nsa.gov> before this can roll in.

Lesson lurned

-- Mark

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Paul Moore Feb. 1, 2018, 4:50 p.m. UTC | #3
On Thu, Feb 1, 2018 at 11:20 AM, Mark Salyzyn <salyzyn@android.com> wrote:
> On 02/01/2018 08:00 AM, Paul Moore wrote:
>>
>> On Thu, Feb 1, 2018 at 10:37 AM, Mark Salyzyn <salyzyn@android.com> wrote:
>>>
>>> In the absence of commit a4298e4522d6 ("net: add SOCK_RCU_FREE socket
>>> flag") and all the associated infrastructure changes to take advantage
>>> of a RCU grace period before freeing, there is a heightened
>>> possibility that a security check is performed while an ill-timed
>>> setsockopt call races in from user space.  It then is prudent to null
>>> check sk_security, and if the case, reject the permissions.
>>>
>>> . . .
>>> ---[ end trace 7b5aaf788fef6174 ]---
>>>
>>> Signed-off-by: Mark Salyzyn <salyzyn@android.com>
>>> Signed-off-by: Paul Moore <paul@linuxfoundation.org>
>>
>> No, in the previous thread I gave my ack, not my sign-off; please be
>> more careful in the future.  It may seem silly, especially in this
>> particular case, but it is an important distinction when things like
>> the DCO are concerned.
>>
>> Anyway, here is my ack again.
>>
>> Acked-by: Paul Moore <paul@paul-moore.com>
>>
> Ok, both Greg KH and yours should be considered Acked-By. Been overstepping
> this boundary for _years_.

One more note, which I didn't realize until I hit reply and the email
bounced: you used a @linuxfoundation.org email address for me which is
clearly not right.  I'm sure it's just a typo, but it's another thing
that needs to be corrected.

> AFAIK Signed-off-by is still pending from Stephen
> Smalley <sds@tycho.nsa.gov> before this can roll in.

Obviously the more acks the better, but you've got mine which should
be sufficient in this case.  The MAINTAINER file currently lists three
people for SELinux: Stephen, Eric, and myself.  I'm responsible for
the traditional maintainer tasks: tree management, PRs to Linus, patch
review, emptying the waste bin at the end of the week, etc.  Stephen
maintains the deep historical knowledge and understanding that comes
with developing the technology/project from it's inception many, many
years ago; no matter how well I may understand SELinux, Stephen will
always have me beat.  Eric is basically my predecessor, having
ventured off to the brave new world of containers and Kubernetes; he
is listed out of respect for his contributions and also to safeguard
us against the all important "bus factor", while he is not as active
as he once was, he still holds a wealth of SELinux knowledge.
Stephen Smalley Feb. 1, 2018, 5:02 p.m. UTC | #4
On Thu, 2018-02-01 at 08:20 -0800, Mark Salyzyn wrote:
> On 02/01/2018 08:00 AM, Paul Moore wrote:
> > On Thu, Feb 1, 2018 at 10:37 AM, Mark Salyzyn <salyzyn@android.com>
> > wrote:
> > > In the absence of commit a4298e4522d6 ("net: add SOCK_RCU_FREE
> > > socket
> > > flag") and all the associated infrastructure changes to take
> > > advantage
> > > of a RCU grace period before freeing, there is a heightened
> > > possibility that a security check is performed while an ill-timed
> > > setsockopt call races in from user space.  It then is prudent to
> > > null
> > > check sk_security, and if the case, reject the permissions.
> > > 
> > > . . .
> > > ---[ end trace 7b5aaf788fef6174 ]---
> > > 
> > > Signed-off-by: Mark Salyzyn <salyzyn@android.com>
> > > Signed-off-by: Paul Moore <paul@linuxfoundation.org>
> > 
> > No, in the previous thread I gave my ack, not my sign-off; please
> > be
> > more careful in the future.  It may seem silly, especially in this
> > particular case, but it is an important distinction when things
> > like
> > the DCO are concerned.
> > 
> > Anyway, here is my ack again.
> > 
> > Acked-by: Paul Moore <paul@paul-moore.com>
> > 
> 
> Ok, both Greg KH and yours should be considered Acked-By. Been 
> overstepping this boundary for _years_. AFAIK Signed-off-by is still 
> pending from Stephen Smalley <sds@tycho.nsa.gov> before this can roll
> in.
> 
> Lesson lurned

No, Paul's Acked-by is sufficient, and at most, I would only add
another Acked-by or Reviewed-by, not a Signed-off-by.  Signed-off-by is
only needed when one had something to do with the writing of the patch
or was in the path by which it was merged.

I don't object to this patch but I have a hard time adding another ack
because I don't truly understand the root cause or how this fixes it. 
Let's say sk_prot_free() calls security_sk_free() calls
selinux_sk_free_security() which sets sk->sk_security to NULL, and then
we proceed to free the sksec and then sk_prot_free() frees the sk
itself.  Now another sock is allocated (or perhaps a different object
altogether), reuses that memory, and whatever sk->sk_security happens
to contain is set to non-NULL.  We'll just blithely proceed past your
check and who knows what will happen from that point onward.

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Greg Kroah-Hartman Feb. 1, 2018, 5:04 p.m. UTC | #5
On Thu, Feb 01, 2018 at 08:20:13AM -0800, Mark Salyzyn wrote:
> On 02/01/2018 08:00 AM, Paul Moore wrote:
> > On Thu, Feb 1, 2018 at 10:37 AM, Mark Salyzyn <salyzyn@android.com> wrote:
> > > In the absence of commit a4298e4522d6 ("net: add SOCK_RCU_FREE socket
> > > flag") and all the associated infrastructure changes to take advantage
> > > of a RCU grace period before freeing, there is a heightened
> > > possibility that a security check is performed while an ill-timed
> > > setsockopt call races in from user space.  It then is prudent to null
> > > check sk_security, and if the case, reject the permissions.
> > > 
> > > . . .
> > > ---[ end trace 7b5aaf788fef6174 ]---
> > > 
> > > Signed-off-by: Mark Salyzyn <salyzyn@android.com>
> > > Signed-off-by: Paul Moore <paul@linuxfoundation.org>
> > No, in the previous thread I gave my ack, not my sign-off; please be
> > more careful in the future.  It may seem silly, especially in this
> > particular case, but it is an important distinction when things like
> > the DCO are concerned.
> > 
> > Anyway, here is my ack again.
> > 
> > Acked-by: Paul Moore <paul@paul-moore.com>
> > 
> Ok, both Greg KH and yours should be considered Acked-By. Been overstepping
> this boundary for _years_. AFAIK Signed-off-by is still pending from Stephen
> Smalley <sds@tycho.nsa.gov> before this can roll in.

An ack is all I need here, or I can just rely on Paul's :)
I'll edit up Paul's when I apply this.

thanks,

greg k-h
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Mark Salyzyn Feb. 1, 2018, 5:23 p.m. UTC | #6
On 02/01/2018 09:02 AM, Stephen Smalley wrote:
> On Thu, 2018-02-01 at 08:20 -0800, Mark Salyzyn wrote:
>> On 02/01/2018 08:00 AM, Paul Moore wrote:
>>> On Thu, Feb 1, 2018 at 10:37 AM, Mark Salyzyn <salyzyn@android.com>
>>> wrote:
>>>> In the absence of commit a4298e4522d6 ("net: add SOCK_RCU_FREE
>>>> socket
>>>> flag") and all the associated infrastructure changes to take
>>>> advantage
>>>> of a RCU grace period before freeing, there is a heightened
>>>> possibility that a security check is performed while an ill-timed
>>>> setsockopt call races in from user space.  It then is prudent to
>>>> null
>>>> check sk_security, and if the case, reject the permissions.
>>>>
>>>> . . .
>>>> ---[ end trace 7b5aaf788fef6174 ]---
>>>>
>>>> Signed-off-by: Mark Salyzyn <salyzyn@android.com>
>>>> Signed-off-by: Paul Moore <paul@linuxfoundation.org>
>>> No, in the previous thread I gave my ack, not my sign-off; please
>>> be
>>> more careful in the future.  It may seem silly, especially in this
>>> particular case, but it is an important distinction when things
>>> like
>>> the DCO are concerned.
>>>
>>> Anyway, here is my ack again.
>>>
>>> Acked-by: Paul Moore <paul@paul-moore.com>
>>>
>> Ok, both Greg KH and yours should be considered Acked-By. Been
>> overstepping this boundary for _years_. AFAIK Signed-off-by is still
>> pending from Stephen Smalley <sds@tycho.nsa.gov> before this can roll
>> in.
>>
>> Lesson lurned
> No, Paul's Acked-by is sufficient, and at most, I would only add
> another Acked-by or Reviewed-by, not a Signed-off-by.  Signed-off-by is
> only needed when one had something to do with the writing of the patch
> or was in the path by which it was merged.
>
> I don't object to this patch but I have a hard time adding another ack
> because I don't truly understand the root cause or how this fixes it.
> Let's say sk_prot_free() calls security_sk_free() calls
> selinux_sk_free_security() which sets sk->sk_security to NULL, and then
> we proceed to free the sksec and then sk_prot_free() frees the sk
> itself.  Now another sock is allocated (or perhaps a different object
> altogether), reuses that memory, and whatever sk->sk_security happens
> to contain is set to non-NULL.  We'll just blithely proceed past your
> check and who knows what will happen from that point onward.
>
The way I read this is this is part of an RCU operation. Multiple 
readers are holding on to the object, but as soon as a new writer comes 
in it _immediately_ frees the sk_security of the 'old' reader copies in 
order to make the 'new' writer copy. Any pending readers continue 
operations until they get tripped on the too aggressively released NULL 
sk_security reference.

Commits came in between 4.4 and 4.9 (edumazet@google.com) to restructure 
and fix this and add the appropriate RCU grace period to the 'old' 
reader copies for the sk_security resource so that it would be freed 
after all the readers had exited. Problem goes away.

My proposal will break any 'old' readers by blocking their access during 
the transition rather than panic the kernel. New readers coming in after 
the writer will progress fine.

This is not a 'bug' in the security layer, this is a bandaid to the 
security layer regarding the bad behavior of the callers.

I have not analyzed the code enough to 100% prove my assertion above, in 
part because I can not duplicate the problem w/o kasan+fuzzing, so still 
treat this as a hunch.

-- Mark

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Greg Kroah-Hartman Feb. 2, 2018, 10:27 a.m. UTC | #7
On Thu, Feb 01, 2018 at 07:37:04AM -0800, Mark Salyzyn wrote:
> In the absence of commit a4298e4522d6 ("net: add SOCK_RCU_FREE socket
> flag") and all the associated infrastructure changes to take advantage
> of a RCU grace period before freeing, there is a heightened
> possibility that a security check is performed while an ill-timed
> setsockopt call races in from user space.  It then is prudent to null
> check sk_security, and if the case, reject the permissions.
> 
> Because of the nature of this problem, hard to duplicate, no clear
> path, this patch is a simplified band-aid for stable trees lacking the
> infrastructure for the series of commits leading up to providing a
> suitable RCU grace period.  This adjustment is orthogonal to
> infrastructure improvements that may nullify the needed check, but
> could be added as good code hygiene in all trees.
> 
> general protection fault: 0000 [#1] PREEMPT SMP KASAN
> CPU: 1 PID: 14233 Comm: syz-executor2 Not tainted 4.4.112-g5f6325b #28
> task: ffff8801d1095f00 task.stack: ffff8800b5950000
> RIP: 0010:[<ffffffff81b69b7e>]  [<ffffffff81b69b7e>] sock_has_perm+0x1fe/0x3e0 security/selinux/hooks.c:4069
> RSP: 0018:ffff8800b5957ce0  EFLAGS: 00010202
> RAX: dffffc0000000000 RBX: 1ffff10016b2af9f RCX: ffffffff81b69b51
> RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000010
> RBP: ffff8800b5957de0 R08: 0000000000000001 R09: 0000000000000001
> R10: 0000000000000000 R11: 1ffff10016b2af68 R12: ffff8800b5957db8
> R13: 0000000000000000 R14: ffff8800b7259f40 R15: 00000000000000d7
> FS:  00007f72f5ae2700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000a2fa38 CR3: 00000001d7980000 CR4: 0000000000160670
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Stack:
>  ffffffff81b69a1f ffff8800b5957d58 00008000b5957d30 0000000041b58ab3
>  ffffffff83fc82f2 ffffffff81b69980 0000000000000246 ffff8801d1096770
>  ffff8801d3165668 ffffffff8157844b ffff8801d1095f00
>  ffff880000000001
> Call Trace:
> [<ffffffff81b6a19d>] selinux_socket_setsockopt+0x4d/0x80 security/selinux/hooks.c:4338
> [<ffffffff81b4873d>] security_socket_setsockopt+0x7d/0xb0 security/security.c:1257
> [<ffffffff82df1ac8>] SYSC_setsockopt net/socket.c:1757 [inline]
> [<ffffffff82df1ac8>] SyS_setsockopt+0xe8/0x250 net/socket.c:1746
> [<ffffffff83776499>] entry_SYSCALL_64_fastpath+0x16/0x92
> Code: c2 42 9b b6 81 be 01 00 00 00 48 c7 c7 a0 cb 2b 84 e8
> f7 2f 6d ff 49 8d 7d 10 48 b8 00 00 00 00 00 fc ff df 48 89
> fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 83 01 00
> 00 41 8b 75 10 31
> RIP  [<ffffffff81b69b7e>] sock_has_perm+0x1fe/0x3e0 security/selinux/hooks.c:4069
> RSP <ffff8800b5957ce0>
> ---[ end trace 7b5aaf788fef6174 ]---
> 
> Signed-off-by: Mark Salyzyn <salyzyn@android.com>
> Signed-off-by: Paul Moore <paul@linuxfoundation.org>
> Signed-off-by: Greg KH <gregkh@linuxfoundation.org>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Stephen Smalley <sds@tycho.nsa.gov>
> Cc: selinux@tycho.nsa.gov
> Cc: linux-security-module@vger.kernel.org
> Cc: Eric Paris <eparis@parisplace.org>
> Cc: Serge E. Hallyn <serge@hallyn.com>
> Cc: stable <stable@vger.kernel.org> # 3.18, 4.4
> Cc: linux-kernel@vger.kernel.org
> ---
> v2: return -EFAULT for null sk_security instead of 0

Now queued up, thanks.

greg k-h
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diff mbox

Patch

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 8644d864e3c1..795efa71d656 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -4342,6 +4342,8 @@  static int sock_has_perm(struct sock *sk, u32 perms)
 	struct common_audit_data ad;
 	struct lsm_network_audit net = {0,};
 
+	if (!sksec)
+		return -EFAULT;
 	if (sksec->sid == SECINITSID_KERNEL)
 		return 0;