linux-kernel - Re: [patch] kexec: potetially using uninitialized variable

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Date:	Fri, 11 Mar 2016 10:47:58 +0100
From:	walter harms <wharms@....de>
To:	Dan Carpenter <dan.carpenter@...cle.com>
CC:	xlpang@...hat.com, Andrew Morton <akpm@...ux-foundation.org>,
	Vivek Goyal <vgoyal@...hat.com>,
	Dave Young <dyoung@...hat.com>, Ingo Molnar <mingo@...nel.org>,
	Toshi Kani <toshi.kani@....com>,
	Mimi Zohar <zohar@...ux.vnet.ibm.com>,
	Minfei Huang <mnfhuang@...il.com>,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [patch] kexec: potetially using uninitialized variable



Am 11.03.2016 10:19, schrieb Dan Carpenter:
> On Fri, Mar 11, 2016 at 04:52:43PM +0800, Xunlei Pang wrote:
>> Hi Dan,
>>
>> On 2016/03/11 at 16:07, Dan Carpenter wrote:
>>> At the end of the function we check if "ret" has a negative error code,
>>> but it seems possible that it is uninitialized.
>>>
>>> Fixes: 12db5562e035 ('kexec: load and relocate purgatory at kernel load time')
>>> Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
>>>
>>> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
>>> index 503bc2d..63d1af3 100644
>>> --- a/kernel/kexec_file.c
>>> +++ b/kernel/kexec_file.c
>>> @@ -795,7 +795,7 @@ out:
>>>  
>>>  static int kexec_apply_relocations(struct kimage *image)
>>>  {
>>> -	int i, ret;
>>> +	int i, ret = 0;
>>>  	struct purgatory_info *pi = &image->purgatory_info;
>>>  	Elf_Shdr *sechdrs = pi->sechdrs;
>>>  
>>
>> Look further, there is a condition at the beginning of the for loop:
>>  
>>
>>         if (sechdrs[i].sh_type != SHT_RELA &&
>>             sechdrs[i].sh_type != SHT_REL)
>>             continue;
>>
>> So, I think that's ok, but I don't konw if GCC is smart enough not to throw warnings.
> 
> Ah, right...
> 
> This wasn't a GCC warning.  GCC misses a lot of uninitialized variable
> bugs so I'm doing this with Smatch.
> 
> Anyway, I'll patch this up in Smatch to not warn about this.
> 

I am not so sure about this. the point should be that the reviewer can read it easily
not if gcc complains or not.

just my 2 cents,

re,
 wh