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[PATCH] file: Add locking to f_getown

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This has been needed for a long time, but now with the advent of a
reference counted struct pid there are real consequences for getting this
wrong.

Someone I think it was Oleg Nesterov pointed out that this construct was
missing locking, when I introduced struct pid.  After taking time to review
the locking construct already present I figured out which lock needs to be
taken.  The other paths that access f_owner.pid take either the f_owner
read or the write lock.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Eric W. Biederman 2006-10-02 02:17:27 -07:00 committed by Linus Torvalds
parent a03fcb730b
commit 43fa1adb93
1 changed files with 2 additions and 0 deletions
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2
fs/fcntl.c
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@ -305,9 +305,11 @@ void f_delown(struct file *filp)
pid_t f_getown(struct file *filp) pid_t f_getown(struct file *filp)
{ {
pid_t pid; pid_t pid;
read_lock(&filp->f_owner.lock);
pid = pid_nr(filp->f_owner.pid); pid = pid_nr(filp->f_owner.pid);
if (filp->f_owner.pid_type == PIDTYPE_PGID) if (filp->f_owner.pid_type == PIDTYPE_PGID)
pid = -pid; pid = -pid;
read_unlock(&filp->f_owner.lock);
return pid; return pid;
} }