Commit f7312735 authored Jun 14, 2017 by Jeff Layton

fs/fcntl: return -ESRCH in f_setown when pid/pgid can't be found

The current implementation of F_SETOWN doesn't properly vet the argument
passed in and only returns an error if INT_MIN is passed in. 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>

parent fc3dc674

fs/fcntl.c

+13 −5

Original line number	Diff line number	Diff line
		@@ -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();
		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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