From 18f05da13dcb4283f61c5a03fbdc48411df6b0f7 Mon Sep 17 00:00:00 2001 From: Hauke Mehrtens Date: Tue, 1 Nov 2022 15:17:03 +0100 Subject: [PATCH] dnsmasq: Backport DHCPv6 server fix (CVE-2022-0934) This backports a commit from upstream dnsmasq to fix CVE-2022-0934. CVE-2022-0934 description: A single-byte, non-arbitrary write/use-after-free flaw was found in dnsmasq. This flaw allows an attacker who sends a crafted packet processed by dnsmasq, potentially causing a denial of service. Signed-off-by: Hauke Mehrtens (cherry picked from commit 002a99eccd75fb653163bae0a1132bd4f494e7ad) --- ...rite-after-free-error-in-DHCPv6-code.patch | 179 ++++++++++++++++++ 1 file changed, 179 insertions(+) create mode 100644 package/network/services/dnsmasq/patches/001-CVE-2022-0934-Fix-write-after-free-error-in-DHCPv6-code.patch diff --git a/package/network/services/dnsmasq/patches/001-CVE-2022-0934-Fix-write-after-free-error-in-DHCPv6-code.patch b/package/network/services/dnsmasq/patches/001-CVE-2022-0934-Fix-write-after-free-error-in-DHCPv6-code.patch new file mode 100644 index 0000000000..4113be99aa --- /dev/null +++ b/package/network/services/dnsmasq/patches/001-CVE-2022-0934-Fix-write-after-free-error-in-DHCPv6-code.patch @@ -0,0 +1,179 @@ +From 03345ecefeb0d82e3c3a4c28f27c3554f0611b39 Mon Sep 17 00:00:00 2001 +From: Simon Kelley +Date: Thu, 31 Mar 2022 21:35:20 +0100 +Subject: Fix write-after-free error in DHCPv6 code. CVE-2022-0934 refers. + +--- + CHANGELOG | 3 +++ + src/rfc3315.c | 48 +++++++++++++++++++++++++++--------------------- + 2 files changed, 30 insertions(+), 21 deletions(-) + +--- a/CHANGELOG ++++ b/CHANGELOG +@@ -92,6 +92,9 @@ version 2.86 + of filename). Thanks to Ed Wildgoose for the initial patch + and motivation for this. + ++ Fix write-after-free error in DHCPv6 server code. ++ CVE-2022-0934 refers. ++ + + version 2.85 + Fix problem with DNS retries in 2.83/2.84. +--- a/src/rfc3315.c ++++ b/src/rfc3315.c +@@ -33,9 +33,9 @@ struct state { + unsigned int mac_len, mac_type; + }; + +-static int dhcp6_maybe_relay(struct state *state, void *inbuff, size_t sz, ++static int dhcp6_maybe_relay(struct state *state, unsigned char *inbuff, size_t sz, + struct in6_addr *client_addr, int is_unicast, time_t now); +-static int dhcp6_no_relay(struct state *state, int msg_type, void *inbuff, size_t sz, int is_unicast, time_t now); ++static int dhcp6_no_relay(struct state *state, int msg_type, unsigned char *inbuff, size_t sz, int is_unicast, time_t now); + static void log6_opts(int nest, unsigned int xid, void *start_opts, void *end_opts); + static void log6_packet(struct state *state, char *type, struct in6_addr *addr, char *string); + static void log6_quiet(struct state *state, char *type, struct in6_addr *addr, char *string); +@@ -104,12 +104,12 @@ unsigned short dhcp6_reply(struct dhcp_c + } + + /* This cost me blood to write, it will probably cost you blood to understand - srk. */ +-static int dhcp6_maybe_relay(struct state *state, void *inbuff, size_t sz, ++static int dhcp6_maybe_relay(struct state *state, unsigned char *inbuff, size_t sz, + struct in6_addr *client_addr, int is_unicast, time_t now) + { + void *end = inbuff + sz; + void *opts = inbuff + 34; +- int msg_type = *((unsigned char *)inbuff); ++ int msg_type = *inbuff; + unsigned char *outmsgtypep; + void *opt; + struct dhcp_vendor *vendor; +@@ -259,15 +259,15 @@ static int dhcp6_maybe_relay(struct stat + return 1; + } + +-static int dhcp6_no_relay(struct state *state, int msg_type, void *inbuff, size_t sz, int is_unicast, time_t now) ++static int dhcp6_no_relay(struct state *state, int msg_type, unsigned char *inbuff, size_t sz, int is_unicast, time_t now) + { + void *opt; +- int i, o, o1, start_opts; ++ int i, o, o1, start_opts, start_msg; + struct dhcp_opt *opt_cfg; + struct dhcp_netid *tagif; + struct dhcp_config *config = NULL; + struct dhcp_netid known_id, iface_id, v6_id; +- unsigned char *outmsgtypep; ++ unsigned char outmsgtype; + struct dhcp_vendor *vendor; + struct dhcp_context *context_tmp; + struct dhcp_mac *mac_opt; +@@ -296,12 +296,13 @@ static int dhcp6_no_relay(struct state * + v6_id.next = state->tags; + state->tags = &v6_id; + +- /* copy over transaction-id, and save pointer to message type */ +- if (!(outmsgtypep = put_opt6(inbuff, 4))) ++ start_msg = save_counter(-1); ++ /* copy over transaction-id */ ++ if (!put_opt6(inbuff, 4)) + return 0; + start_opts = save_counter(-1); +- state->xid = outmsgtypep[3] | outmsgtypep[2] << 8 | outmsgtypep[1] << 16; +- ++ state->xid = inbuff[3] | inbuff[2] << 8 | inbuff[1] << 16; ++ + /* We're going to be linking tags from all context we use. + mark them as unused so we don't link one twice and break the list */ + for (context_tmp = state->context; context_tmp; context_tmp = context_tmp->current) +@@ -347,7 +348,7 @@ static int dhcp6_no_relay(struct state * + (msg_type == DHCP6REQUEST || msg_type == DHCP6RENEW || msg_type == DHCP6RELEASE || msg_type == DHCP6DECLINE)) + + { +- *outmsgtypep = DHCP6REPLY; ++ outmsgtype = DHCP6REPLY; + o1 = new_opt6(OPTION6_STATUS_CODE); + put_opt6_short(DHCP6USEMULTI); + put_opt6_string("Use multicast"); +@@ -619,11 +620,11 @@ static int dhcp6_no_relay(struct state * + struct dhcp_netid *solicit_tags; + struct dhcp_context *c; + +- *outmsgtypep = DHCP6ADVERTISE; ++ outmsgtype = DHCP6ADVERTISE; + + if (opt6_find(state->packet_options, state->end, OPTION6_RAPID_COMMIT, 0)) + { +- *outmsgtypep = DHCP6REPLY; ++ outmsgtype = DHCP6REPLY; + state->lease_allocate = 1; + o = new_opt6(OPTION6_RAPID_COMMIT); + end_opt6(o); +@@ -809,7 +810,7 @@ static int dhcp6_no_relay(struct state * + int start = save_counter(-1); + + /* set reply message type */ +- *outmsgtypep = DHCP6REPLY; ++ outmsgtype = DHCP6REPLY; + state->lease_allocate = 1; + + log6_quiet(state, "DHCPREQUEST", NULL, ignore ? _("ignored") : NULL); +@@ -924,7 +925,7 @@ static int dhcp6_no_relay(struct state * + int address_assigned = 0; + + /* set reply message type */ +- *outmsgtypep = DHCP6REPLY; ++ outmsgtype = DHCP6REPLY; + + log6_quiet(state, msg_type == DHCP6RENEW ? "DHCPRENEW" : "DHCPREBIND", NULL, NULL); + +@@ -1057,7 +1058,7 @@ static int dhcp6_no_relay(struct state * + int good_addr = 0; + + /* set reply message type */ +- *outmsgtypep = DHCP6REPLY; ++ outmsgtype = DHCP6REPLY; + + log6_quiet(state, "DHCPCONFIRM", NULL, NULL); + +@@ -1121,7 +1122,7 @@ static int dhcp6_no_relay(struct state * + log6_quiet(state, "DHCPINFORMATION-REQUEST", NULL, ignore ? _("ignored") : state->hostname); + if (ignore) + return 0; +- *outmsgtypep = DHCP6REPLY; ++ outmsgtype = DHCP6REPLY; + tagif = add_options(state, 1); + break; + } +@@ -1130,7 +1131,7 @@ static int dhcp6_no_relay(struct state * + case DHCP6RELEASE: + { + /* set reply message type */ +- *outmsgtypep = DHCP6REPLY; ++ outmsgtype = DHCP6REPLY; + + log6_quiet(state, "DHCPRELEASE", NULL, NULL); + +@@ -1195,7 +1196,7 @@ static int dhcp6_no_relay(struct state * + case DHCP6DECLINE: + { + /* set reply message type */ +- *outmsgtypep = DHCP6REPLY; ++ outmsgtype = DHCP6REPLY; + + log6_quiet(state, "DHCPDECLINE", NULL, NULL); + +@@ -1275,7 +1276,12 @@ static int dhcp6_no_relay(struct state * + } + + } +- ++ ++ /* Fill in the message type. Note that we store the offset, ++ not a direct pointer, since the packet memory may have been ++ reallocated. */ ++ ((unsigned char *)(daemon->outpacket.iov_base))[start_msg] = outmsgtype; ++ + log_tags(tagif, state->xid); + log6_opts(0, state->xid, daemon->outpacket.iov_base + start_opts, daemon->outpacket.iov_base + save_counter(-1)); + -- 2.30.2