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authorCyrill Gorcunov <gorcunov@openvz.org>2012-10-20 00:56:53 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2012-10-20 01:07:47 +0400
commitbbc2e3ef87851bc5430b2b4cf4ca3a2f29baeda6 (patch)
treed9cef396c8370184f23e99480725aa8fde4bea08 /include/linux/pid_namespace.h
parentdc36d7e7cd422d69b15e7ec7cc1f021f581a6b6d (diff)
downloadlinux-bbc2e3ef87851bc5430b2b4cf4ca3a2f29baeda6.tar.xz
pidns: remove recursion from free_pid_ns()
free_pid_ns() operates in a recursive fashion: free_pid_ns(parent) put_pid_ns(parent) kref_put(&ns->kref, free_pid_ns); free_pid_ns thus if there was a huge nesting of namespaces the userspace may trigger avalanche calling of free_pid_ns leading to kernel stack exhausting and a panic eventually. This patch turns the recursion into an iterative loop. Based on a patch by Andrew Vagin. [akpm@linux-foundation.org: export put_pid_ns() to modules] Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Andrew Vagin <avagin@openvz.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: Greg KH <greg@kroah.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/pid_namespace.h')
-rw-r--r--include/linux/pid_namespace.h8
1 files changed, 1 insertions, 7 deletions
diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
index 00474b047145..65e3e87eacc5 100644
--- a/include/linux/pid_namespace.h
+++ b/include/linux/pid_namespace.h
@@ -47,15 +47,9 @@ static inline struct pid_namespace *get_pid_ns(struct pid_namespace *ns)
}
extern struct pid_namespace *copy_pid_ns(unsigned long flags, struct pid_namespace *ns);
-extern void free_pid_ns(struct kref *kref);
extern void zap_pid_ns_processes(struct pid_namespace *pid_ns);
extern int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd);
-
-static inline void put_pid_ns(struct pid_namespace *ns)
-{
- if (ns != &init_pid_ns)
- kref_put(&ns->kref, free_pid_ns);
-}
+extern void put_pid_ns(struct pid_namespace *ns);
#else /* !CONFIG_PID_NS */
#include <linux/err.h>