ipvs: flush defense_work before module unload

net/ipv4/ipvs/ip_vs_core.c

	module_exit
	    ip_vs_cleanup
		ip_vs_control_cleanup
		    cancel_rearming_delayed_work
	// done

This is unsafe.  The module may be unloaded and the memory may be freed
while defense_work's handler is still running/preempted.

Do flush_work(&defense_work.work) after cancel_rearming_delayed_work().

Alternatively, we could add flush_work() to cancel_rearming_delayed_work(),
but note that we can't change cancel_delayed_work() in the same manner
because it may be called from atomic context.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/net/ipv4/ipvs/ip_vs_ctl.c b/net/ipv4/ipvs/ip_vs_ctl.c
index b3050a6..342e836 100644 (file)
--- a/net/ipv4/ipvs/ip_vs_ctl.c
+++ b/net/ipv4/ipvs/ip_vs_ctl.c
@@ -2387,6 +2387,7 @@ void ip_vs_control_cleanup(void)
        EnterFunction(2);
        ip_vs_trash_cleanup();
        cancel_rearming_delayed_work(&defense_work);
+       flush_work_keventd(&defense_work.work);
        ip_vs_kill_estimator(&ip_vs_stats);
        unregister_sysctl_table(sysctl_header);
        proc_net_remove("ip_vs_stats");