Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 9915672d authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

af_unix: limit unix_tot_inflight 



Vegard Nossum found a unix socket OOM was possible, posting an exploit
program.

My analysis is we can eat all LOWMEM memory before unix_gc() being
called from unix_release_sock(). Moreover, the thread blocked in
unix_gc() can consume huge amount of time to perform cleanup because of
huge working set.

One way to handle this is to have a sensible limit on unix_tot_inflight,
tested from wait_for_unix_gc() and to force a call to unix_gc() if this
limit is hit.

This solves the OOM and also reduce overall latencies, and should not
slowdown normal workloads.

Reported-by: default avatarVegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent cf41a51d

net/unix/garbage.c

+7 −0
Original line number Diff line number Diff line
@@ -259,9 +259,16 @@ static void inc_inflight_move_tail(struct unix_sock *u) 
}



static bool gc_in_progress = false;

#define UNIX_INFLIGHT_TRIGGER_GC 16000



void wait_for_unix_gc(void)

{

	/*

	 * If number of inflight sockets is insane,

	 * force a garbage collect right now.

	 */

	if (unix_tot_inflight > UNIX_INFLIGHT_TRIGGER_GC && !gc_in_progress)

		unix_gc();

	wait_event(unix_gc_wait, gc_in_progress == false);

}