2014-05-15 21:55:55

by Rickard Strandqvist

[permalink] [raw]
Subject: [PATCH] Fix for possible null pointer dereference in auth.c

There is otherwise a risk of a possible null pointer dereference.

Was largely found by using a static code analysis program called cppcheck.

Signed-off-by: Rickard Strandqvist <[email protected]>
---
net/sunrpc/auth.c | 10 +++++++---
1 fil ändrad, 7 tillägg(+), 3 borttagningar(-)

diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c
index 5285ead..3a55698 100644
--- a/net/sunrpc/auth.c
+++ b/net/sunrpc/auth.c
@@ -801,10 +801,14 @@ rpcauth_invalcred(struct rpc_task *task)
{
struct rpc_cred *cred = task->tk_rqstp->rq_cred;

- dprintk("RPC: %5u invalidating %s cred %p\n",
- task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
- if (cred)
+ if (cred) {
+ dprintk("RPC: %5u invalidating %s cred %p\n",
+ task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
+
clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
+ }
+ else
+ dprintk("RPC: %5u invalidating is NULL\n", task->tk_pid);
}

int
--
1.7.10.4



2014-05-15 22:07:02

by Trond Myklebust

[permalink] [raw]
Subject: Re: [PATCH] Fix for possible null pointer dereference in auth.c

On Thu, May 15, 2014 at 5:56 PM, Rickard Strandqvist
<[email protected]> wrote:
> There is otherwise a risk of a possible null pointer dereference.
>
> Was largely found by using a static code analysis program called cppcheck.
>
> Signed-off-by: Rickard Strandqvist <[email protected]>
> ---
> net/sunrpc/auth.c | 10 +++++++---
> 1 fil ändrad, 7 tillägg(+), 3 borttagningar(-)
>
> diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c
> index 5285ead..3a55698 100644
> --- a/net/sunrpc/auth.c
> +++ b/net/sunrpc/auth.c
> @@ -801,10 +801,14 @@ rpcauth_invalcred(struct rpc_task *task)
> {
> struct rpc_cred *cred = task->tk_rqstp->rq_cred;
>
> - dprintk("RPC: %5u invalidating %s cred %p\n",
> - task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
> - if (cred)
> + if (cred) {
> + dprintk("RPC: %5u invalidating %s cred %p\n",
> + task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
> +
> clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
> + }
> + else
> + dprintk("RPC: %5u invalidating is NULL\n", task->tk_pid);
> }
>
>

Can you please explain how we can get to rpcauth_invalcred() without a
valid cred pointer? I'm not seeing it...

Cheers
Trond

2014-05-16 12:19:36

by Sergei Shtylyov

[permalink] [raw]
Subject: Re: [PATCH] Fix for possible null pointer dereference in auth.c

Hello.

On 16-05-2014 1:56, Rickard Strandqvist wrote:

> There is otherwise a risk of a possible null pointer dereference.

> Was largely found by using a static code analysis program called cppcheck.

> Signed-off-by: Rickard Strandqvist <[email protected]>
> ---
> net/sunrpc/auth.c | 10 +++++++---
> 1 fil ändrad, 7 tillägg(+), 3 borttagningar(-)

> diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c
> index 5285ead..3a55698 100644
> --- a/net/sunrpc/auth.c
> +++ b/net/sunrpc/auth.c
> @@ -801,10 +801,14 @@ rpcauth_invalcred(struct rpc_task *task)
> {
> struct rpc_cred *cred = task->tk_rqstp->rq_cred;
>
> - dprintk("RPC: %5u invalidating %s cred %p\n",
> - task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
> - if (cred)
> + if (cred) {
> + dprintk("RPC: %5u invalidating %s cred %p\n",
> + task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
> +
> clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
> + }
> + else

} and *else* should be on the same line, and there should be {} in the
*else* arm since there's {} in the *if* arm already, according to
Documentation/CodingStyle.

> + dprintk("RPC: %5u invalidating is NULL\n", task->tk_pid);

That's not a proper English, I'm afraid.

> }

WBR, Sergei



2014-05-15 22:10:54

by Rickard Strandqvist

[permalink] [raw]
Subject: Re: [PATCH] Fix for possible null pointer dereference in auth.c

Hi

I do not know, I'm not an expert on this code.
But since there before was a if (cred) someone must have thought this
could happen.

Best regards
Rickard Strandqvist


2014-05-16 0:07 GMT+02:00 Trond Myklebust <[email protected]>:
> On Thu, May 15, 2014 at 5:56 PM, Rickard Strandqvist
> <[email protected]> wrote:
>> There is otherwise a risk of a possible null pointer dereference.
>>
>> Was largely found by using a static code analysis program called cppcheck.
>>
>> Signed-off-by: Rickard Strandqvist <[email protected]>
>> ---
>> net/sunrpc/auth.c | 10 +++++++---
>> 1 fil ändrad, 7 tillägg(+), 3 borttagningar(-)
>>
>> diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c
>> index 5285ead..3a55698 100644
>> --- a/net/sunrpc/auth.c
>> +++ b/net/sunrpc/auth.c
>> @@ -801,10 +801,14 @@ rpcauth_invalcred(struct rpc_task *task)
>> {
>> struct rpc_cred *cred = task->tk_rqstp->rq_cred;
>>
>> - dprintk("RPC: %5u invalidating %s cred %p\n",
>> - task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
>> - if (cred)
>> + if (cred) {
>> + dprintk("RPC: %5u invalidating %s cred %p\n",
>> + task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
>> +
>> clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
>> + }
>> + else
>> + dprintk("RPC: %5u invalidating is NULL\n", task->tk_pid);
>> }
>>
>>
>
> Can you please explain how we can get to rpcauth_invalcred() without a
> valid cred pointer? I'm not seeing it...
>
> Cheers
> Trond

2014-05-17 17:17:29

by Trond Myklebust

[permalink] [raw]
Subject: Re: [PATCH] Fix for possible null pointer dereference in auth.c

On Sat, May 17, 2014 at 12:36 PM, Rickard Strandqvist
<[email protected]> wrote:
> Hi
>
> I have made a new patch according Sergei specification.
>

I'll be happy to apply this patch once someone explains to me why we
can't just remove that check for cred != NULL, however I'm not
applying a patch purely in order to silence a warning from cppcheck.

Cheers,
Trond

> But there remains Tronds question though.
>
> Best regards
> Rickard Strandqvist
>
>
> 2014-05-16 14:19 GMT+02:00 Sergei Shtylyov <[email protected]>:
>> Hello.
>>
>>
>> On 16-05-2014 1:56, Rickard Strandqvist wrote:
>>
>>> There is otherwise a risk of a possible null pointer dereference.
>>
>>
>>> Was largely found by using a static code analysis program called cppcheck.
>>
>>
>>> Signed-off-by: Rickard Strandqvist
>>> <[email protected]>
>>> ---
>>> net/sunrpc/auth.c | 10 +++++++---
>>> 1 fil ändrad, 7 tillägg(+), 3 borttagningar(-)
>>
>>
>>> diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c
>>> index 5285ead..3a55698 100644
>>> --- a/net/sunrpc/auth.c
>>> +++ b/net/sunrpc/auth.c
>>> @@ -801,10 +801,14 @@ rpcauth_invalcred(struct rpc_task *task)
>>> {
>>> struct rpc_cred *cred = task->tk_rqstp->rq_cred;
>>>
>>> - dprintk("RPC: %5u invalidating %s cred %p\n",
>>> - task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
>>> - if (cred)
>>> + if (cred) {
>>> + dprintk("RPC: %5u invalidating %s cred %p\n",
>>> + task->tk_pid, cred->cr_auth->au_ops->au_name,
>>> cred);
>>> +
>>> clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
>>> + }
>>> + else
>>
>>
>> } and *else* should be on the same line, and there should be {} in the
>> *else* arm since there's {} in the *if* arm already, according to
>> Documentation/CodingStyle.
>>
>>
>>> + dprintk("RPC: %5u invalidating is NULL\n", task->tk_pid);
>>
>>
>> That's not a proper English, I'm afraid.
>>
>>> }
>>
>>
>> WBR, Sergei
>>
>>



--
Trond Myklebust

Linux NFS client maintainer, PrimaryData

[email protected]

2014-05-17 16:36:14

by Rickard Strandqvist

[permalink] [raw]
Subject: Re: [PATCH] Fix for possible null pointer dereference in auth.c

Hi

I have made a new patch according Sergei specification.

But there remains Tronds question though.

Best regards
Rickard Strandqvist


2014-05-16 14:19 GMT+02:00 Sergei Shtylyov <[email protected]>:
> Hello.
>
>
> On 16-05-2014 1:56, Rickard Strandqvist wrote:
>
>> There is otherwise a risk of a possible null pointer dereference.
>
>
>> Was largely found by using a static code analysis program called cppcheck.
>
>
>> Signed-off-by: Rickard Strandqvist
>> <[email protected]>
>> ---
>> net/sunrpc/auth.c | 10 +++++++---
>> 1 fil ändrad, 7 tillägg(+), 3 borttagningar(-)
>
>
>> diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c
>> index 5285ead..3a55698 100644
>> --- a/net/sunrpc/auth.c
>> +++ b/net/sunrpc/auth.c
>> @@ -801,10 +801,14 @@ rpcauth_invalcred(struct rpc_task *task)
>> {
>> struct rpc_cred *cred = task->tk_rqstp->rq_cred;
>>
>> - dprintk("RPC: %5u invalidating %s cred %p\n",
>> - task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
>> - if (cred)
>> + if (cred) {
>> + dprintk("RPC: %5u invalidating %s cred %p\n",
>> + task->tk_pid, cred->cr_auth->au_ops->au_name,
>> cred);
>> +
>> clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
>> + }
>> + else
>
>
> } and *else* should be on the same line, and there should be {} in the
> *else* arm since there's {} in the *if* arm already, according to
> Documentation/CodingStyle.
>
>
>> + dprintk("RPC: %5u invalidating is NULL\n", task->tk_pid);
>
>
> That's not a proper English, I'm afraid.
>
>> }
>
>
> WBR, Sergei
>
>


Attachments:
0001-Fix-for-possible-null-pointer-dereferenc.patch (1.17 kB)