tree 73fc82e92a119dcf1a0ce4e2ca45ef410165776f
parent 5c1aba467828bf0574ec5754c84884d573f590af
author Eric Dumazet <eric.dumazet@gmail.com> 1300632006 +0100
committer Patrick McHardy <kaber@trash.net> 1300632006 +0100

netfilter: xtables: fix reentrancy

commit f3c5c1bfd4308 (make ip_tables reentrant) introduced a race in
handling the stackptr restore, at the end of ipt_do_table()

We should do it before the call to xt_info_rdunlock_bh(), or we allow
cpu preemption and another cpu overwrites stackptr of original one.

A second fix is to change the underflow test to check the origptr value
instead of 0 to detect underflow, or else we allow a jump from different
hooks.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>