| Message ID | 1458666173-24318-6-git-send-email-fw@strlen.de |
|---|---|
| State | Changes Requested |
| Delegated to: | Pablo Neira |
| Headers | show |
On Tue, Mar 22, 2016 at 06:02:53PM +0100, Florian Westphal wrote: > Ben Hawkes reported an out-of-bounds write in mark_source_chains(). > This was caused by improper underflow check -- we should have bailed > earlier. > > The underflow check has been fixed in the preceeding change > ("netfilter: x_tables: fix unconditional helper"). > > Just to be safe also add checks to mark_source_chains() in case we have other > bugs that would cause such a condition. > > Signed-off-by: Florian Westphal <fw@strlen.de> > --- > net/ipv4/netfilter/arp_tables.c | 8 +++++--- > net/ipv4/netfilter/ip_tables.c | 4 ++++ > net/ipv6/netfilter/ip6_tables.c | 4 ++++ > 3 files changed, 13 insertions(+), 3 deletions(-) > > diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c > index a2002ff..13266f4 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); > @@ -682,10 +686,8 @@ 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; > diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c > index 45b1d97..c4836f0 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 (WARN_ON(pos + size >= newinfo->size)) > + return 0; This got WARN_ON(), but not in other spots. I'll place 1 to 4 in the nf tree, then I suggest we take a little bit more time to follow up to validate that we can actually trigger from all possible corners. Thanks Florian! -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c index a2002ff..13266f4 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); @@ -682,10 +686,8 @@ 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; diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c index 45b1d97..c4836f0 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 (WARN_ON(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 (WARN_ON(newpos >= newinfo->size)) + return 0; } e = (struct ipt_entry *) (entry0 + newpos); diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c index 85c0942..ab7cdbf 100644 --- a/net/ipv6/netfilter/ip6_tables.c +++ b/net/ipv6/netfilter/ip6_tables.c @@ -532,6 +532,8 @@ mark_source_chains(const struct xt_table_info *newinfo, size = e->next_offset; e = (struct ip6t_entry *) (entry0 + pos + size); + if (pos + size >= newinfo->size) + return 0; e->counters.pcnt = pos; pos += size; } else { @@ -553,6 +555,8 @@ 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 ip6t_entry *) (entry0 + newpos);
Ben Hawkes reported an out-of-bounds write in mark_source_chains(). This was caused by improper underflow check -- we should have bailed earlier. The underflow check has been fixed in the preceeding change ("netfilter: x_tables: fix unconditional helper"). Just to be safe also add checks to mark_source_chains() in case we have other bugs that would cause such a condition. Signed-off-by: Florian Westphal <fw@strlen.de> --- net/ipv4/netfilter/arp_tables.c | 8 +++++--- net/ipv4/netfilter/ip_tables.c | 4 ++++ net/ipv6/netfilter/ip6_tables.c | 4 ++++ 3 files changed, 13 insertions(+), 3 deletions(-)