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/ip_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/ip_tables.c')
| -rw-r--r-- | net/ipv4/netfilter/ip_tables.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c index 631c100a13384..e301a3db4717a 100644 --- a/net/ipv4/netfilter/ip_tables.c +++ b/net/ipv4/netfilter/ip_tables.c @@ -520,6 +520,8 @@ mark_source_chains(const struct xt_table_info *newinfo, size = e->next_offset; e = (struct ipt_entry *) (entry0 + pos + size); + if (pos + size >= newinfo->size) + return 0; e->counters.pcnt = pos; pos += size; } else { @@ -541,6 +543,8 @@ 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 ipt_entry *) (entry0 + newpos); |