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SubjectRe: [PATCH] fs/fcntl: return -ESRCH in f_setown when pid/pgid can't be found
yes,  look good to me.

but I found the another issue. if the pass argument is -1. by the spec describe,
type should be assigned to PIDTYPE_MAX, Do you think that it deserve another patch ?

Thanks
zhongjiang

On 2017/6/14 22:52, Jeff Layton wrote:
> The current implementation of F_SETOWN doesn't properly vet the argument
> passed in. It never returns an error. If the argument doesn't specify a
> valid pid/pgid, then we just end up cleaning out the file->f_owner
> structure.
>
> What we really want is to only clean that out only in the case where
> userland passed in an argument of 0. For anything else, we want to
> return ESRCH if it doesn't refer to a valid pid.
>
> The relevant POSIX spec page is here:
>
> http://pubs.opengroup.org/onlinepubs/9699919799/functions/fcntl.html
>
> Cc: Jiri Slaby <jslaby@suse.cz>
> Cc: zhong jiang <zhongjiang@huawei.com>
> Signed-off-by: Jeff Layton <jlayton@redhat.com>
> ---
> fs/fcntl.c | 18 +++++++++++++-----
> 1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/fs/fcntl.c b/fs/fcntl.c
> index 693322e28751..afed3b364979 100644
> --- a/fs/fcntl.c
> +++ b/fs/fcntl.c
> @@ -112,8 +112,9 @@ EXPORT_SYMBOL(__f_setown);
> int f_setown(struct file *filp, unsigned long arg, int force)
> {
> enum pid_type type;
> - struct pid *pid;
> - int who = arg;
> + struct pid *pid = NULL;
> + int who = arg, ret = 0;
> +
> type = PIDTYPE_PID;
> if (who < 0) {
> /* avoid overflow below */
> @@ -123,12 +124,19 @@ int f_setown(struct file *filp, unsigned long arg, int force)
> type = PIDTYPE_PGID;
> who = -who;
> }
> +
> rcu_read_lock();
> - pid = find_vpid(who);
> - __f_setown(filp, pid, type, force);
> + if (who) {
> + pid = find_vpid(who);
> + if (!pid)
> + ret = -ESRCH;
> + }
> +
> + if (!ret)
> + __f_setown(filp, pid, type, force);
> rcu_read_unlock();
>
> - return 0;
> + return ret;
> }
> EXPORT_SYMBOL(f_setown);
>


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