I'm sorry to send you the wrong patch,
I'll send a new patch to you later.
Thanks
Tang
发件人: Mike Snitzer <snitzer@xxxxxxxxxx>
收件人: tang.junhui@xxxxxxxxxx,
抄送: zhang.kai16@xxxxxxxxxx, dm-devel@xxxxxxxxxx, agk@xxxxxxxxxx
日期: 2016/11/03 23:33
主题: Re: [dm-devel] dm mpath: add check for count of groups to avoid wild pointer access
发件人: dm-devel-bounces@xxxxxxxxxx
On Thu, Nov 03 2016 at 6:49am -0400,
tang.junhui@xxxxxxxxxx <tang.junhui@xxxxxxxxxx> wrote:
> From: "tang.junhui" <tang.junhui@xxxxxxxxxx>
>
> pg is not assigned to a group address when count of multipath groups
> is zero in bypass_pg_num(), then it is used in bypass_pg(), which may
> cause wild pointer access.
>
> Signed-off-by: tang.junhui <tang.junhui@xxxxxxxxxx>
> ---
> drivers/md/dm-mpath.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
> index d376dc8..8c1359c 100644
> --- a/drivers/md/dm-mpath.c
> +++ b/drivers/md/dm-mpath.c
> @@ -1084,7 +1084,7 @@ static int switch_pg_num(struct multipath *m, const char *pgstr)
> char dummy;
>
> if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
> - (pgnum > m->nr_priority_groups)) {
> + !m->nr_priority_groups || (pgnum > m->nr_priority_groups)) {
> DMWARN("invalid PG number supplied to switch_pg_num");
> return -EINVAL;
> }
> --
> 2.8.1.windows.1
>
>
You mention bypass_pg_num() going on to hit a NULL/"wild" pointer. Not
immediately seeing the relation between switch_pg_num() and
bypass_pg_num(). But shouldn't bypass_pg_num() have improved bounds
checking (and/or NULL pointer checks) too?
Maybe your patch was applied with an offset and it modified
switch_pg_num() when you really meant to modify bypass_pg_num()?
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