linux-kernel - Re: [HPDD-discuss] [PATCH] staging: lustre: include: lustre_update.h: Fix for possible null pointer dereference

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Message-ID: <54CA8ED8.5040202@cray.com>
Date:	Thu, 29 Jan 2015 13:49:44 -0600
From:	Frank Zago <fzago@...y.com>
To:	Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
CC:	Oleg Drokin <oleg.drokin@...el.com>,
	Andreas Dilger <andreas.dilger@...el.com>,
	"HPDD-discuss@...ts.01.org" <HPDD-discuss@...ts.01.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [HPDD-discuss] [PATCH] staging: lustre: include: lustre_update.h:
 Fix for possible null pointer dereference

On 01/29/2015 01:47 PM, Rickard Strandqvist wrote:
> 2015-01-29 20:40 GMT+01:00 Frank Zago <fzago@...y.com>:
>> On 01/29/2015 12:47 PM, Rickard Strandqvist wrote:
>>>
>>> Fix a possible null pointer dereference, there is
>>> otherwise a risk of a possible null pointer dereference.
>>>
>>> This was found using a static code analysis program called cppcheck
>>>
>>> Signed-off-by: Rickard Strandqvist
>>> <rickard_strandqvist@...ctrumdigital.se>
>>> ---
>>>    drivers/staging/lustre/lustre/include/lustre_update.h |    4 +++-
>>>    1 file changed, 3 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/staging/lustre/lustre/include/lustre_update.h
>>> b/drivers/staging/lustre/lustre/include/lustre_update.h
>>> index 84defce..00e1361 100644
>>> --- a/drivers/staging/lustre/lustre/include/lustre_update.h
>>> +++ b/drivers/staging/lustre/lustre/include/lustre_update.h
>>> @@ -165,12 +165,14 @@ static inline int update_get_reply_buf(struct
>>> update_reply *reply, void **buf,
>>>          int  result;
>>>
>>>          ptr = update_get_buf_internal(reply, index, &size);
>>> +
>>> +       LASSERT((ptr != NULL && size >= sizeof(int)));
>>
>>
>> Now size is tested before result. So it could assert if result < 0, while
>> the function would have returned before.
>>
>>
>>> +
>>>          result = *(int *)ptr;
>>>
>>>          if (result < 0)
>>>                  return result;
>>>
>>> -       LASSERT((ptr != NULL && size >= sizeof(int)));
>>>          *buf = ptr + sizeof(int);
>>>          return size - sizeof(int);
>>>    }
>>>
>>
>
>
>
> But if prt is null krachar on the line:
> result = *(int *)ptr;
>
> Maybe there should be two LASSERT then.


Yes, that would be safer.

Frank.
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