Re: [PATCH v3] mdadm: monitor: fix nullptr dereference when get_md_name() returns NULL

[NeilBrown <neilb@suse.de>]

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On Tue, 19 May 2015 22:02:46 +0300 Sergey Vidishev <sergeyv@yandex-team.ru>
wrote:

> >From fce3be7200e84665cdae58ba44d5c61af094af3b Mon Sep 17 00:00:00 2001
> From: Sergey Vidishev <sergeyv@yandex-team.ru>
> Date: Tue, 19 May 2015 20:34:58 +0300
> Subject: [PATCH] mdadm: monitor: fix nullptr dereference when get_md_name()
>  returns NULL
> 
> Function add_new_arrays() expects that function get_md_name() should
> return pointer to devname, but also get_md_name() may return NULL. So
> check the pointer before use it in add_new_arrays().
> 
> Signed-off-by: Sergey Vidishev <sergeyv@yandex-team.ru>
> ---
> 
> v2 -> v3: - continue instead of return
>           - avoid mem leak (thanks to David F.)
> v1 -> v2: more verbose commit message
> 
>  Monitor.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/Monitor.c b/Monitor.c
> index 1cd378b..a530032 100644
> --- a/Monitor.c
> +++ b/Monitor.c
> @@ -687,6 +687,7 @@ static int add_new_arrays(struct mdstat_ent *mdstat, struct state **statelist,
>  {
>  	struct mdstat_ent *mse;
>  	int new_found = 0;
> +	char *name;
>  
>  	for (mse=mdstat; mse; mse=mse->next)
>  		if (mse->devnm[0] &&
> @@ -697,7 +698,14 @@ static int add_new_arrays(struct mdstat_ent *mdstat, struct state **statelist,
>  			struct state *st = xcalloc(1, sizeof *st);
>  			mdu_array_info_t array;
>  			int fd;
> -			st->devname = xstrdup(get_md_name(mse->devnm));
> +
> +			name = get_md_name(mse->devnm);
> +			if (!name) {
> +				free(st);
> +				continue;
> +			}
> +
> +			st->devname = xstrdup(name);
>  			if ((fd = open(st->devname, O_RDONLY)) < 0 ||
>  			    ioctl(fd, GET_ARRAY_INFO, &array)< 0) {
>  				/* no such array */


Applied, thanks.
And thanks David for the review help!

NeilBrown


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