diff options
| author | Florian Westphal <fw@strlen.de> | 2018-02-07 13:46:25 +0100 |
|---|---|---|
| committer | Todd Kjos <tkjos@google.com> | 2018-07-05 18:02:06 -0700 |
| commit | dd5ce79caedcc7585314ef7243d589682f35f179 (patch) | |
| tree | 6dda97672359b758429f561f79097ebd08ea7cda | |
| parent | c5f3f40625c3318f18ecb045f8c26fc5fb3a00f8 (diff) | |
netfilter: add back stackpointer size checksASB-2018-07-05_4.4-o-release
commit 57ebd808a97d7c5b1e1afb937c2db22beba3c1f8 upstream.
The rationale for removing the check is only correct for rulesets
generated by ip(6)tables.
In iptables, a jump can only occur to a user-defined chain, i.e.
because we size the stack based on number of user-defined chains we
cannot exceed stack size.
However, the underlying binary format has no such restriction,
and the validation step only ensures that the jump target is a
valid rule start point.
IOW, its possible to build a rule blob that has no user-defined
chains but does contain a jump.
If this happens, no jump stack gets allocated and crash occurs
because no jumpstack was allocated.
Fixes: 7814b6ec6d0d6 ("netfilter: xtables: don't save/restore jumpstack offset")
Reported-by: syzbot+e783f671527912cd9403@syzkaller.appspotmail.com
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | net/ipv4/netfilter/arp_tables.c | 4 | ||||
| -rw-r--r-- | net/ipv4/netfilter/ip_tables.c | 4 | ||||
| -rw-r--r-- | net/ipv6/netfilter/ip6_tables.c | 4 |
3 files changed, 12 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c index 6e3e0e8b1ce3..cff58f7ee559 100644 --- a/net/ipv4/netfilter/arp_tables.c +++ b/net/ipv4/netfilter/arp_tables.c @@ -329,6 +329,10 @@ unsigned int arpt_do_table(struct sk_buff *skb, } if (table_base + v != arpt_next_entry(e)) { + if (unlikely(stackidx >= private->stacksize)) { + verdict = NF_DROP; + break; + } jumpstack[stackidx++] = e; } diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c index a399c5419622..760c81dfbee8 100644 --- a/net/ipv4/netfilter/ip_tables.c +++ b/net/ipv4/netfilter/ip_tables.c @@ -408,6 +408,10 @@ ipt_do_table(struct sk_buff *skb, } if (table_base + v != ipt_next_entry(e) && !(e->ip.flags & IPT_F_GOTO)) { + if (unlikely(stackidx >= private->stacksize)) { + verdict = NF_DROP; + break; + } jumpstack[stackidx++] = e; pr_debug("Pushed %p into pos %u\n", e, stackidx - 1); diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c index 22f39e00bef3..8f676ca6ce86 100644 --- a/net/ipv6/netfilter/ip6_tables.c +++ b/net/ipv6/netfilter/ip6_tables.c @@ -425,6 +425,10 @@ ip6t_do_table(struct sk_buff *skb, } if (table_base + v != ip6t_next_entry(e) && !(e->ipv6.flags & IP6T_F_GOTO)) { + if (unlikely(stackidx >= private->stacksize)) { + verdict = NF_DROP; + break; + } jumpstack[stackidx++] = e; } |