diff options
Diffstat (limited to 'netfilter-x_tables-deal-with-bogus-nextoffset-values.patch')
| -rw-r--r-- | netfilter-x_tables-deal-with-bogus-nextoffset-values.patch | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/netfilter-x_tables-deal-with-bogus-nextoffset-values.patch b/netfilter-x_tables-deal-with-bogus-nextoffset-values.patch new file mode 100644 index 000000000..ebfe1716f --- /dev/null +++ b/netfilter-x_tables-deal-with-bogus-nextoffset-values.patch @@ -0,0 +1,150 @@ +Subject: [PATCH nf] netfilter: x_tables: deal with bogus nextoffset values +From: Florian Westphal <fw () strlen ! de> +Date: 2016-03-10 0:56:02 + +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. + +Problem is that xt_entry_foreach() macro stops iterating once e->next_offset +is out of bounds, assuming this is the last entry. + +With malformed data thats not necessarily the case so we can +write outside of allocated area later as we might not have walked the +entire blob. + +Fix this by simplifying mark_source_chains -- it already has to check +if nextoff is in range to catch invalid jumps, so just do the check +when we move to a next entry as well. + +Signed-off-by: Florian Westphal <fw@strlen.de> +--- + net/ipv4/netfilter/arp_tables.c | 16 ++++++++-------- + net/ipv4/netfilter/ip_tables.c | 15 ++++++++------- + net/ipv6/netfilter/ip6_tables.c | 13 ++++++------- + 3 files changed, 22 insertions(+), 22 deletions(-) + +diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c +index b488cac..5a0b591 100644 +--- a/net/ipv4/netfilter/arp_tables.c ++++ b/net/ipv4/netfilter/arp_tables.c +@@ -437,6 +437,10 @@ static int mark_source_chains(const struct xt_table_info *newinfo, + + /* Move along one */ + size = e->next_offset; ++ ++ if (pos + size > newinfo->size - sizeof(*e)) ++ return 0; ++ + e = (struct arpt_entry *) + (entry0 + pos + size); + e->counters.pcnt = pos; +@@ -447,14 +451,6 @@ static int mark_source_chains(const struct xt_table_info *newinfo, + if (strcmp(t->target.u.user.name, + XT_STANDARD_TARGET) == 0 && + newpos >= 0) { +- if (newpos > newinfo->size - +- sizeof(struct arpt_entry)) { +- duprintf("mark_source_chains: " +- "bad verdict (%i)\n", +- newpos); +- return 0; +- } +- + /* This a jump; chase it. */ + duprintf("Jump rule %u -> %u\n", + pos, newpos); +@@ -462,6 +458,10 @@ static int mark_source_chains(const struct xt_table_info *newinfo, + /* ... this is a fallthru */ + newpos = pos + e->next_offset; + } ++ ++ if (newpos > newinfo->size - sizeof(*e)) ++ return 0; ++ + e = (struct arpt_entry *) + (entry0 + newpos); + e->counters.pcnt = pos; +diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c +index b99affa..ceb995f 100644 +--- a/net/ipv4/netfilter/ip_tables.c ++++ b/net/ipv4/netfilter/ip_tables.c +@@ -519,6 +519,10 @@ mark_source_chains(const struct xt_table_info *newinfo, + + /* Move along one */ + size = e->next_offset; ++ ++ if (pos + size > newinfo->size - sizeof(*e)) ++ return 0; ++ + e = (struct ipt_entry *) + (entry0 + pos + size); + e->counters.pcnt = pos; +@@ -529,13 +533,6 @@ mark_source_chains(const struct xt_table_info *newinfo, + if (strcmp(t->target.u.user.name, + XT_STANDARD_TARGET) == 0 && + newpos >= 0) { +- if (newpos > newinfo->size - +- sizeof(struct ipt_entry)) { +- duprintf("mark_source_chains: " +- "bad verdict (%i)\n", +- newpos); +- return 0; +- } + /* This a jump; chase it. */ + duprintf("Jump rule %u -> %u\n", + pos, newpos); +@@ -543,6 +540,10 @@ mark_source_chains(const struct xt_table_info *newinfo, + /* ... this is a fallthru */ + newpos = pos + e->next_offset; + } ++ ++ if (newpos > newinfo->size - sizeof(*e)) ++ return 0; ++ + e = (struct ipt_entry *) + (entry0 + newpos); + e->counters.pcnt = pos; +diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c +index 99425cf..d88a794 100644 +--- a/net/ipv6/netfilter/ip6_tables.c ++++ b/net/ipv6/netfilter/ip6_tables.c +@@ -531,6 +531,8 @@ mark_source_chains(const struct xt_table_info *newinfo, + + /* Move along one */ + size = e->next_offset; ++ if (pos + size > newinfo->size - sizeof(*e)) ++ return 0; + e = (struct ip6t_entry *) + (entry0 + pos + size); + e->counters.pcnt = pos; +@@ -541,13 +543,6 @@ mark_source_chains(const struct xt_table_info *newinfo, + if (strcmp(t->target.u.user.name, + XT_STANDARD_TARGET) == 0 && + newpos >= 0) { +- if (newpos > newinfo->size - +- sizeof(struct ip6t_entry)) { +- duprintf("mark_source_chains: " +- "bad verdict (%i)\n", +- newpos); +- return 0; +- } + /* This a jump; chase it. */ + duprintf("Jump rule %u -> %u\n", + pos, newpos); +@@ -555,6 +550,10 @@ mark_source_chains(const struct xt_table_info *newinfo, + /* ... this is a fallthru */ + newpos = pos + e->next_offset; + } ++ ++ if (newpos > newinfo->size - sizeof(*e)) ++ return 0; ++ + e = (struct ip6t_entry *) + (entry0 + newpos); + e->counters.pcnt = pos; +-- +2.4.10 |