Andrew Geissler | 615f2f1 | 2022-07-15 14:00:58 -0500 | [diff] [blame] | 1 | From 3cdecc159e0f417a2f8d43d99632af26beea630f Mon Sep 17 00:00:00 2001 |
| 2 | From: Simon Kelley <simon@thekelleys.org.uk> |
| 3 | Date: Thu, 31 Mar 2022 21:35:20 +0100 |
| 4 | Subject: [PATCH] Fix write-after-free error in DHCPv6 code. CVE-2022-0934 |
| 5 | refers. |
| 6 | |
| 7 | CVE: CVE-2022-0934 |
| 8 | |
| 9 | Upstream-Status: Backport |
| 10 | [https://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commitdiff;h=03345ecefe] |
| 11 | |
| 12 | Signed-off-by: Yi Zhao <yi.zhao@windriver.com> |
| 13 | --- |
| 14 | CHANGELOG | 3 +++ |
| 15 | src/rfc3315.c | 48 +++++++++++++++++++++++++++--------------------- |
| 16 | 2 files changed, 30 insertions(+), 21 deletions(-) |
| 17 | |
| 18 | diff --git a/CHANGELOG b/CHANGELOG |
| 19 | index 5e54df9..a28da2a 100644 |
| 20 | --- a/CHANGELOG |
| 21 | +++ b/CHANGELOG |
| 22 | @@ -1,4 +1,7 @@ |
| 23 | version 2.86 |
| 24 | + Fix write-after-free error in DHCPv6 server code. |
| 25 | + CVE-2022-0934 refers. |
| 26 | + |
| 27 | Handle DHCPREBIND requests in the DHCPv6 server code. |
| 28 | Thanks to Aichun Li for spotting this omission, and the initial |
| 29 | patch. |
| 30 | diff --git a/src/rfc3315.c b/src/rfc3315.c |
| 31 | index 5c2ff97..6ecfeeb 100644 |
| 32 | --- a/src/rfc3315.c |
| 33 | +++ b/src/rfc3315.c |
| 34 | @@ -33,9 +33,9 @@ struct state { |
| 35 | unsigned int mac_len, mac_type; |
| 36 | }; |
| 37 | |
| 38 | -static int dhcp6_maybe_relay(struct state *state, void *inbuff, size_t sz, |
| 39 | +static int dhcp6_maybe_relay(struct state *state, unsigned char *inbuff, size_t sz, |
| 40 | struct in6_addr *client_addr, int is_unicast, time_t now); |
| 41 | -static int dhcp6_no_relay(struct state *state, int msg_type, void *inbuff, size_t sz, int is_unicast, time_t now); |
| 42 | +static int dhcp6_no_relay(struct state *state, int msg_type, unsigned char *inbuff, size_t sz, int is_unicast, time_t now); |
| 43 | static void log6_opts(int nest, unsigned int xid, void *start_opts, void *end_opts); |
| 44 | static void log6_packet(struct state *state, char *type, struct in6_addr *addr, char *string); |
| 45 | static void log6_quiet(struct state *state, char *type, struct in6_addr *addr, char *string); |
| 46 | @@ -104,12 +104,12 @@ unsigned short dhcp6_reply(struct dhcp_context *context, int interface, char *if |
| 47 | } |
| 48 | |
| 49 | /* This cost me blood to write, it will probably cost you blood to understand - srk. */ |
| 50 | -static int dhcp6_maybe_relay(struct state *state, void *inbuff, size_t sz, |
| 51 | +static int dhcp6_maybe_relay(struct state *state, unsigned char *inbuff, size_t sz, |
| 52 | struct in6_addr *client_addr, int is_unicast, time_t now) |
| 53 | { |
| 54 | void *end = inbuff + sz; |
| 55 | void *opts = inbuff + 34; |
| 56 | - int msg_type = *((unsigned char *)inbuff); |
| 57 | + int msg_type = *inbuff; |
| 58 | unsigned char *outmsgtypep; |
| 59 | void *opt; |
| 60 | struct dhcp_vendor *vendor; |
| 61 | @@ -259,15 +259,15 @@ static int dhcp6_maybe_relay(struct state *state, void *inbuff, size_t sz, |
| 62 | return 1; |
| 63 | } |
| 64 | |
| 65 | -static int dhcp6_no_relay(struct state *state, int msg_type, void *inbuff, size_t sz, int is_unicast, time_t now) |
| 66 | +static int dhcp6_no_relay(struct state *state, int msg_type, unsigned char *inbuff, size_t sz, int is_unicast, time_t now) |
| 67 | { |
| 68 | void *opt; |
| 69 | - int i, o, o1, start_opts; |
| 70 | + int i, o, o1, start_opts, start_msg; |
| 71 | struct dhcp_opt *opt_cfg; |
| 72 | struct dhcp_netid *tagif; |
| 73 | struct dhcp_config *config = NULL; |
| 74 | struct dhcp_netid known_id, iface_id, v6_id; |
| 75 | - unsigned char *outmsgtypep; |
| 76 | + unsigned char outmsgtype; |
| 77 | struct dhcp_vendor *vendor; |
| 78 | struct dhcp_context *context_tmp; |
| 79 | struct dhcp_mac *mac_opt; |
| 80 | @@ -296,12 +296,13 @@ static int dhcp6_no_relay(struct state *state, int msg_type, void *inbuff, size_ |
| 81 | v6_id.next = state->tags; |
| 82 | state->tags = &v6_id; |
| 83 | |
| 84 | - /* copy over transaction-id, and save pointer to message type */ |
| 85 | - if (!(outmsgtypep = put_opt6(inbuff, 4))) |
| 86 | + start_msg = save_counter(-1); |
| 87 | + /* copy over transaction-id */ |
| 88 | + if (!put_opt6(inbuff, 4)) |
| 89 | return 0; |
| 90 | start_opts = save_counter(-1); |
| 91 | - state->xid = outmsgtypep[3] | outmsgtypep[2] << 8 | outmsgtypep[1] << 16; |
| 92 | - |
| 93 | + state->xid = inbuff[3] | inbuff[2] << 8 | inbuff[1] << 16; |
| 94 | + |
| 95 | /* We're going to be linking tags from all context we use. |
| 96 | mark them as unused so we don't link one twice and break the list */ |
| 97 | for (context_tmp = state->context; context_tmp; context_tmp = context_tmp->current) |
| 98 | @@ -347,7 +348,7 @@ static int dhcp6_no_relay(struct state *state, int msg_type, void *inbuff, size_ |
| 99 | (msg_type == DHCP6REQUEST || msg_type == DHCP6RENEW || msg_type == DHCP6RELEASE || msg_type == DHCP6DECLINE)) |
| 100 | |
| 101 | { |
| 102 | - *outmsgtypep = DHCP6REPLY; |
| 103 | + outmsgtype = DHCP6REPLY; |
| 104 | o1 = new_opt6(OPTION6_STATUS_CODE); |
| 105 | put_opt6_short(DHCP6USEMULTI); |
| 106 | put_opt6_string("Use multicast"); |
| 107 | @@ -619,11 +620,11 @@ static int dhcp6_no_relay(struct state *state, int msg_type, void *inbuff, size_ |
| 108 | struct dhcp_netid *solicit_tags; |
| 109 | struct dhcp_context *c; |
| 110 | |
| 111 | - *outmsgtypep = DHCP6ADVERTISE; |
| 112 | + outmsgtype = DHCP6ADVERTISE; |
| 113 | |
| 114 | if (opt6_find(state->packet_options, state->end, OPTION6_RAPID_COMMIT, 0)) |
| 115 | { |
| 116 | - *outmsgtypep = DHCP6REPLY; |
| 117 | + outmsgtype = DHCP6REPLY; |
| 118 | state->lease_allocate = 1; |
| 119 | o = new_opt6(OPTION6_RAPID_COMMIT); |
| 120 | end_opt6(o); |
| 121 | @@ -809,7 +810,7 @@ static int dhcp6_no_relay(struct state *state, int msg_type, void *inbuff, size_ |
| 122 | int start = save_counter(-1); |
| 123 | |
| 124 | /* set reply message type */ |
| 125 | - *outmsgtypep = DHCP6REPLY; |
| 126 | + outmsgtype = DHCP6REPLY; |
| 127 | state->lease_allocate = 1; |
| 128 | |
| 129 | log6_quiet(state, "DHCPREQUEST", NULL, ignore ? _("ignored") : NULL); |
| 130 | @@ -924,7 +925,7 @@ static int dhcp6_no_relay(struct state *state, int msg_type, void *inbuff, size_ |
| 131 | int address_assigned = 0; |
| 132 | |
| 133 | /* set reply message type */ |
| 134 | - *outmsgtypep = DHCP6REPLY; |
| 135 | + outmsgtype = DHCP6REPLY; |
| 136 | |
| 137 | log6_quiet(state, msg_type == DHCP6RENEW ? "DHCPRENEW" : "DHCPREBIND", NULL, NULL); |
| 138 | |
| 139 | @@ -1057,7 +1058,7 @@ static int dhcp6_no_relay(struct state *state, int msg_type, void *inbuff, size_ |
| 140 | int good_addr = 0; |
| 141 | |
| 142 | /* set reply message type */ |
| 143 | - *outmsgtypep = DHCP6REPLY; |
| 144 | + outmsgtype = DHCP6REPLY; |
| 145 | |
| 146 | log6_quiet(state, "DHCPCONFIRM", NULL, NULL); |
| 147 | |
| 148 | @@ -1121,7 +1122,7 @@ static int dhcp6_no_relay(struct state *state, int msg_type, void *inbuff, size_ |
| 149 | log6_quiet(state, "DHCPINFORMATION-REQUEST", NULL, ignore ? _("ignored") : state->hostname); |
| 150 | if (ignore) |
| 151 | return 0; |
| 152 | - *outmsgtypep = DHCP6REPLY; |
| 153 | + outmsgtype = DHCP6REPLY; |
| 154 | tagif = add_options(state, 1); |
| 155 | break; |
| 156 | } |
| 157 | @@ -1130,7 +1131,7 @@ static int dhcp6_no_relay(struct state *state, int msg_type, void *inbuff, size_ |
| 158 | case DHCP6RELEASE: |
| 159 | { |
| 160 | /* set reply message type */ |
| 161 | - *outmsgtypep = DHCP6REPLY; |
| 162 | + outmsgtype = DHCP6REPLY; |
| 163 | |
| 164 | log6_quiet(state, "DHCPRELEASE", NULL, NULL); |
| 165 | |
| 166 | @@ -1195,7 +1196,7 @@ static int dhcp6_no_relay(struct state *state, int msg_type, void *inbuff, size_ |
| 167 | case DHCP6DECLINE: |
| 168 | { |
| 169 | /* set reply message type */ |
| 170 | - *outmsgtypep = DHCP6REPLY; |
| 171 | + outmsgtype = DHCP6REPLY; |
| 172 | |
| 173 | log6_quiet(state, "DHCPDECLINE", NULL, NULL); |
| 174 | |
| 175 | @@ -1275,7 +1276,12 @@ static int dhcp6_no_relay(struct state *state, int msg_type, void *inbuff, size_ |
| 176 | } |
| 177 | |
| 178 | } |
| 179 | - |
| 180 | + |
| 181 | + /* Fill in the message type. Note that we store the offset, |
| 182 | + not a direct pointer, since the packet memory may have been |
| 183 | + reallocated. */ |
| 184 | + ((unsigned char *)(daemon->outpacket.iov_base))[start_msg] = outmsgtype; |
| 185 | + |
| 186 | log_tags(tagif, state->xid); |
| 187 | log6_opts(0, state->xid, daemon->outpacket.iov_base + start_opts, daemon->outpacket.iov_base + save_counter(-1)); |
| 188 | |
| 189 | -- |
| 190 | 2.25.1 |
| 191 | |