[openwrt/openwrt] dnsmasq: Backport DHCPv6 server fix (CVE-2022-0934)
LEDE Commits
lede-commits at lists.infradead.org
Mon Dec 26 06:25:18 PST 2022
ansuel pushed a commit to openwrt/openwrt.git, branch openwrt-21.02:
https://git.openwrt.org/18f05da13dcb4283f61c5a03fbdc48411df6b0f7
commit 18f05da13dcb4283f61c5a03fbdc48411df6b0f7
Author: Hauke Mehrtens <hauke at hauke-m.de>
AuthorDate: Tue Nov 1 15:17:03 2022 +0100
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 <hauke at hauke-m.de>
(cherry picked from commit 002a99eccd75fb653163bae0a1132bd4f494e7ad)
---
...Fix-write-after-free-error-in-DHCPv6-code.patch | 179 +++++++++++++++++++++
1 file changed, 179 insertions(+)
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 <simon at thekelleys.org.uk>
+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));
+
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