Re: [PATCH 01/39] memcg_write_event_control(): fix a user-triggerable oops

Michal Hocko
2024-07-30T07:13:41Z

On Tue 30-07-24 01:15:47, viro@kernel.org wrote:
> From: Al Viro <viro@zeniv.linux.org.uk>
>
> we are *not* guaranteed that anything past the terminating NUL
> is mapped (let alone initialized with anything sane).
>
> [the sucker got moved in mainline]
>

You could have preserved
Fixes: 0dea116876ee ("cgroup: implement eventfd-based generic API for notifications")
Cc: stable

> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

and
Acked-by: Michal Hocko <mhocko@suse.com>

> ---
> mm/memcontrol-v1.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/mm/memcontrol-v1.c b/mm/memcontrol-v1.c
> index 2aeea4d8bf8e..417c96f2da28 100644
> --- a/mm/memcontrol-v1.c
> +++ b/mm/memcontrol-v1.c
> @@ -1842,9 +1842,12 @@ static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
> buf = endp + 1;
>
> cfd = simple_strtoul(buf, &endp, 10);
> - if ((*endp != ' ') && (*endp != '\0'))
> + if (*endp == '\0')
> + buf = endp;
> + else if (*endp == ' ')
> + buf = endp + 1;
> + else
> return -EINVAL;
> - buf = endp + 1;
>
> event = kzalloc(sizeof(*event), GFP_KERNEL);
> if (!event)
> --
> 2.39.2
>

--
Michal Hocko
SUSE Labs