[dm-devel] [PATCH V2] libmultipath: free pp if store_path fails in disassemble_map

[Zhiqiang Liu]

On 2020/8/10 20:20, Martin Wilck wrote:
> Hello Liu,
> 
> On Fri, 2020-07-24 at 09:40 +0800, Zhiqiang Liu wrote:
>> In disassemble_map func, one pp will be allocated and stored in
>> pgp->paths. However, if store_path fails, pp will not be freed,
>> then memory leak problem occurs.
>>
>> Here, we will call free_path to free pp when store_path fails.
>>
>> Signed-off-by: Zhiqiang Liu <liuzhiqiang26 at huawei.com>
>> Signed-off-by: lixiaokeng <lixiaokeng at huawei.com>
>> ---
>> V1->V2: update based on ups/submit-2007 branch.
>>
>>  libmultipath/dmparser.c | 9 +++++++--
>>  1 file changed, 7 insertions(+), 2 deletions(-)
>>
> 
> thanks for the patch. I'd suggest to do this without the pp_alloc_flag
> variable, by pulling the store_path() call into the if (!pp)
> conditional and treating failure differently in both branches of the
> conditional. (Side note: if we introduce a boolean like this, we should
> use "bool" as the variable type).
> 
> Unless you object, I'll add that change on top of my submit-2007
> series, giving you appropriate credits.
> 
Thanks for you review.

You are free to deal with the patch.


> @Ben, @Christophe: I've been considering for some time to start
> handling cases like this with __attribute__((cleanup(f)))) (
> https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html).
> That could reduce the amount of goto clauses for error handling
> significantly. It would be a major change in coding style though. What
> do you think?
> 
> Regards,
> Martin
> 
> 
>> diff --git a/libmultipath/dmparser.c b/libmultipath/dmparser.c
>> index b9858fa5..8a0501ba 100644
>> --- a/libmultipath/dmparser.c
>> +++ b/libmultipath/dmparser.c
>> @@ -143,6 +143,7 @@ int disassemble_map(const struct _vector
>> *pathvec,
>>  	int def_minio = 0;
>>  	struct path * pp;
>>  	struct pathgroup * pgp;
>> +	int pp_alloc_flag = 0;
>>
>>  	assert(pathvec != NULL);
>>  	p = params;
>> @@ -292,6 +293,7 @@ int disassemble_map(const struct _vector
>> *pathvec,
>>
>>  		for (j = 0; j < num_paths; j++) {
>>  			pp = NULL;
>> +			pp_alloc_flag = 0;
>>  			p += get_word(p, &word);
>>
>>  			if (!word)
>> @@ -304,13 +306,16 @@ int disassemble_map(const struct _vector
>> *pathvec,
>>
>>  				if (!pp)
>>  					goto out1;
>> -
>> +				pp_alloc_flag = 1;
>>  				strlcpy(pp->dev_t, word, BLK_DEV_SIZE);
>>  			}
>>  			FREE(word);
>>
>> -			if (store_path(pgp->paths, pp))
>> +			if (store_path(pgp->paths, pp)) {
>> +				if (pp_alloc_flag)
>> +					free_path(pp);
>>  				goto out;
>> +			}
>>
>>  			pgp->id ^= (long)pp;
>>  			pp->pgindex = i + 1;
> 
> 
> 
> .
>