af_unix: limit unix_tot_inflight
authorEric Dumazet <eric.dumazet@gmail.com>
Wed, 24 Nov 2010 17:15:27 +0000 (09:15 -0800)
committerDavid S. Miller <davem@davemloft.net>
Wed, 24 Nov 2010 17:15:27 +0000 (09:15 -0800)
commit9915672d41273f5b77f1b3c29b391ffb7732b84b
tree191dbf657535e49265be7664755890630e69e329
parentcf41a51db89850033efc11c18a5257de810b5417
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: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/unix/garbage.c