diff options
| author | Florian Westphal <fw@strlen.de> | 2018-02-07 15:46:25 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-03-15 12:54:23 +0300 |
| commit | 638c2e4eff89aae86593e80ac2be01eee195fccb (patch) | |
| tree | be7a70057b4557e3bd5fb00c75991dd3a2f358ec | |
| parent | 310f286ded5f1f7fd72dcb1cff936c0a02d5a4d2 (diff) | |
| download | linux-638c2e4eff89aae86593e80ac2be01eee195fccb.tar.xz | |
netfilter: add back stackpointer size checks
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 | 7 | ||||
| -rw-r--r-- | net/ipv6/netfilter/ip6_tables.c | 4 |
3 files changed, 14 insertions, 1 deletions
diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c index 9e2770fd00be..aa4c3b7f7da4 100644 --- a/net/ipv4/netfilter/arp_tables.c +++ b/net/ipv4/netfilter/arp_tables.c @@ -257,6 +257,10 @@ 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 39286e543ee6..cadb82a906b8 100644 --- a/net/ipv4/netfilter/ip_tables.c +++ b/net/ipv4/netfilter/ip_tables.c @@ -335,8 +335,13 @@ ipt_do_table(struct sk_buff *skb, continue; } if (table_base + v != ipt_next_entry(e) && - !(e->ip.flags & IPT_F_GOTO)) + !(e->ip.flags & IPT_F_GOTO)) { + if (unlikely(stackidx >= private->stacksize)) { + verdict = NF_DROP; + break; + } jumpstack[stackidx++] = e; + } e = get_entry(table_base, v); continue; diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c index 01bd3ee5ebc6..a0a31972fc75 100644 --- a/net/ipv6/netfilter/ip6_tables.c +++ b/net/ipv6/netfilter/ip6_tables.c @@ -357,6 +357,10 @@ 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; } |