[dm-devel] [PATCH] segment faulty occured in add_feature()

[Benjamin Marzinski]

On Tue, Nov 01, 2016 at 08:44:49AM +0800, huang.wei56 at zte.com.cn wrote:

ACK

-Ben

> From: wei huang <huang.wei56 at zte.com.cn>
> 
> Problem:
> Multipathd segment faulty occured when device policy was configured in multipath.conf as follow:
> #This is a device configuration just for COMPELNT device
> devices {
>        device {
>                vendor                  COMPELNT
>                dev_loss_tmo            120
>                scheduler               deadline
>        }
> }
> 
> The call trace is:
> Program received signal SIGSEGV, Segmentation fault.
> 0x00007f4eaaf49251 in __strstr_sse2 () from /lib64/libc.so.6
> (gdb) bt
> #0  0x00007f4eaaf49251 in __strstr_sse2 () from /lib64/libc.so.6
> #1  0x00007f4eabba879c in add_feature (f=f at entry=0x211b248, n=n at entry=0x7f4eabbc530a queue_if_no_path)
>     at structs.c:524
> #2  0x00007f4eabba6993 in merge_hwe (src=0x2148c70, dst=0x211b220) at config.c:359
> #3  factorize_hwtable (hw=0x214b800, n=n at entry=77) at config.c:452
> #4  0x00007f4eabba7850 in load_config (file=file at entry=0x4144c8 /etc/multipath.conf) at config.c:651
> #5  0x0000000000408959 in reconfigure (vecs=vecs at entry=0x2128ae0) at main.c:2078
> #6  0x00000000004063c6 in child (param=0x0) at main.c:2483
> #7  main (argc=<optimized out>, argv=<optimized out>) at main.c:2725
> (gdb) up
> #1  0x00007f4eabba879c in add_feature (f=f at entry=0x211b248, n=n at entry=0x7f4eabbc530a queue_if_no_path)
>     at structs.c:524
> 524             if (strstr(*f, n))
> (gdb) p *f
>  = 0x0
> 
> Reasons:
> When multipathd loads config, it will call merge_hwe() to merge the features between default_hw[] and config.
> If the vender is not configured features in default_hw[], dst->features's value will be null. So strstr()'s first
> parameter *f is null in add_feature(),too.
> 
> Signed-off-by: wei huang <huang.wei56 at zte.com.cn>
> ---
>  libmultipath/structs.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/libmultipath/structs.c b/libmultipath/structs.c
> index fee58e5..f673325 100644
> --- a/libmultipath/structs.c
> +++ b/libmultipath/structs.c
> @@ -520,6 +520,17 @@ add_feature (char **f, char *n)
>  	if (!n || *n == '0')
>  		return 0;
>  
> +	/* default feature is null */
> +	if(!*f)
> +	{
> +		l = asprintf(&t, "1 %s", n);
> +		if(l == -1)
> +			return 1;
> +			
> +		*f = t;
> +		return 0;
> +	}
> +
>  	/* Check if feature is already present */
>  	if (strstr(*f, n))
>  		return 0;
> -- 
> 2.8.1.windows.1