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authorEric Dumazet <eric.dumazet@gmail.com>2011-03-20 15:40:06 +0100
committerPatrick McHardy <kaber@trash.net>2011-03-20 15:40:06 +0100
commitdb856674ac69e31946e56085239757cca3f7655f (patch)
tree73fc82e92a119dcf1a0ce4e2ca45ef410165776f /net/ipv6
parent5c1aba467828bf0574ec5754c84884d573f590af (diff)
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>
Diffstat (limited to 'net/ipv6')
-rw-r--r--net/ipv6/netfilter/ip6_tables.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index c9598a9067d7..0b2af9b85cec 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -410,7 +410,7 @@ ip6t_do_table(struct sk_buff *skb,
verdict = (unsigned)(-v) - 1;
break;
}
- if (*stackptr == 0)
+ if (*stackptr <= origptr)
e = get_entry(table_base,
private->underflow[hook]);
else
@@ -441,8 +441,8 @@ ip6t_do_table(struct sk_buff *skb,
break;
} while (!acpar.hotdrop);
- xt_info_rdunlock_bh();
*stackptr = origptr;
+ xt_info_rdunlock_bh();
#ifdef DEBUG_ALLOW_ALL
return NF_ACCEPT;