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

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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>
This commit is contained in:
Jeff Layton 2017-06-14 09:11:54 -04:00
parent fc3dc67471
commit f73127356f
1 changed files with 13 additions and 5 deletions
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18
fs/fcntl.c
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@ -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);