diff options
| author | Florian Westphal <fw@strlen.de> | 2016-04-01 14:17:21 +0200 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2016-04-14 00:30:34 +0200 |
| commit | f24e230d257af1ad7476c6e81a8dc3127a74204e (patch) | |
| tree | 941d889997d998419e5d3a6e5486188dfe5457a7 /net/ipv4/netfilter/arp_tables.c | |
| parent | 7d45a04cbc2683f9552572850f1c711d9b96dd26 (diff) | |
| download | linux-f24e230d257af1ad7476c6e81a8dc3127a74204e.tar.gz | |
netfilter: x_tables: don't move to non-existent next rule
Ben Hawkes says:
In the mark_source_chains function (net/ipv4/netfilter/ip_tables.c) it
is possible for a user-supplied ipt_entry structure to have a large
next_offset field. This field is not bounds checked prior to writing a
counter value at the supplied offset.
Base chains enforce absolute verdict.
User defined chains are supposed to end with an unconditional return,
xtables userspace adds them automatically.
But if such return is missing we will move to non-existent next rule.
Reported-by: Ben Hawkes <hawkes@google.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/ipv4/netfilter/arp_tables.c')
| -rw-r--r-- | net/ipv4/netfilter/arp_tables.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c index 4133b0f513afe5..82a434bf865366 100644 --- a/net/ipv4/netfilter/arp_tables.c +++ b/net/ipv4/netfilter/arp_tables.c @@ -439,6 +439,8 @@ static int mark_source_chains(const struct xt_table_info *newinfo, size = e->next_offset; e = (struct arpt_entry *) (entry0 + pos + size); + if (pos + size >= newinfo->size) + return 0; e->counters.pcnt = pos; pos += size; } else { @@ -461,6 +463,8 @@ static int mark_source_chains(const struct xt_table_info *newinfo, } else { /* ... this is a fallthru */ newpos = pos + e->next_offset; + if (newpos >= newinfo->size) + return 0; } e = (struct arpt_entry *) (entry0 + newpos); @@ -691,10 +695,8 @@ static int translate_table(struct xt_table_info *newinfo, void *entry0, } } - if (!mark_source_chains(newinfo, repl->valid_hooks, entry0)) { - duprintf("Looping hook\n"); + if (!mark_source_chains(newinfo, repl->valid_hooks, entry0)) return -ELOOP; - } /* Finally, each sanity check must pass */ i = 0; |