The failure path removes the allocated PIDs from the wrong namespace.
This could lead to us inadvertently reusing PIDs in the leaf namespace
and leaking PIDs in parent namespaces.

Fixes: 95846ecf9dac ("pid: replace pid bitmap implementation with IDR API")
Cc: <[email protected]>
Signed-off-by: Matthew Wilcox <[email protected]>
Acked-by: "Eric W. Biederman" <[email protected]>
Reviewed-by: Oleg Nesterov <[email protected]>
---
 kernel/pid.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/pid.c b/kernel/pid.c
index b2f6c506035da..20881598bdfac 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -233,8 +233,10 @@ struct pid *alloc_pid(struct pid_namespace *ns)
 
 out_free:
        spin_lock_irq(&pidmap_lock);
-       while (++i <= ns->level)
-               idr_remove(&ns->idr, (pid->numbers + i)->nr);
+       while (++i <= ns->level) {
+               upid = pid->numbers + i;
+               idr_remove(&upid->ns->idr, upid->nr);
+       }
 
        /* On failure to allocate the first pid, reset the state */
        if (ns->pid_allocated == PIDNS_ADDING)
-- 
2.19.2

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