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 <[email protected]>
---
fs/fcntl.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/fs/fcntl.c b/fs/fcntl.c
index 821ebb9..b1dd4d4 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -305,9 +305,11 @@ void f_delown(struct file *filp)
pid_t f_getown(struct file *filp)
{
pid_t pid;
+ read_lock(&filp->f_owner.lock);
pid = pid_nr(filp->f_owner.pid);
if (filp->f_owner.pid_type == PIDTYPE_PGID)
pid = -pid;
+ read_unlock(&filp->f_owner.lock);
return pid;
}
--
1.4.2.rc3.g7e18e-dirty
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