dhcpcd: dhcpcd: Denial of Service via NULL pointer dereference during configuration option parsing

A NULL pointer dereference occurs in Roy Marples NetworkConfiguration/dhcpcd 10.3.0 while parsing configuration options. In parse_option() (src/if-options.c:1886), the code performs a member access on a NULL pointer of type 'struct dhcp_opt' when an unexpected/invalid option token or parsing state causes the lookup to yield NULL. The instrumented fuzzing build reports 'runtime error: member access within null pointer of type struct dhcp_opt' and aborts.

Dhcpcd: dhcpcd infinite loop and out-of-bounds read via zero-length ipv6 nd option in router advertisement handling

A flaw was found in dhcpcd's IPv6 Neighbor Discovery Router Advertisement processing. A specially crafted IPv6 Router Advertisement containing a zero-length Neighbor Discovery option can bypass validation during packet storage and later be reparsed without adequate validation, causing the parser to enter a non-advancing loop. Successful exploitation may result in excessive CPU consumption, leading to a denial of service.

dhcpcd Heap Use-After-Free via Control Socket Handling

dhcpcd through 10.3.2, fixed in commit 78ea09e, contains a heap use-after-free vulnerability in the control socket handling within src/control.c that allows local unprivileged attackers to trigger memory corruption when privilege separation is disabled. Attackers can connect to the control socket and send a privileged command such as -x, causing control_recvdata() to free the client object while the same READ+HANGUP event subsequently reaches control_hangup() with the stale pointer, resulting in a use-after-free condition exploitable in deployments using --disable-privsep or where privsep initialization has failed with the control socket operating in mode 0666.

dhcpcd Memory Leak DoS via IPv6 Router Advertisement Handling

dhcpcd through 10.3.2, fixed in commit 708b4a5, contains a memory leak vulnerability in the IPv6 Router Advertisement route information handling that allows an unauthenticated same-link attacker to cause denial of service by sending crafted Router Advertisements. Attackers can repeatedly send Router Advertisements containing Route Information options with a lifetime of zero, triggering unfreed allocations in routeinfo_findalloc() that cause linear memory exhaustion and eventual daemon crash.

dhcpcd Stack Out-of-Bounds Write in dhcp6_makemessage()

dhcpcd through 10.3.2, fixed in commit 2f00c7b, contains a one-byte stack out-of-bounds write vulnerability in dhcp6_makemessage() in src/dhcp6.c that allows unauthenticated same-link attackers to write beyond a fixed local buffer by serializing an oversized RFC6603 OPTION_PD_EXCLUDE option body. Attackers can send a crafted DHCPv6 ADVERTISE message containing an IA_PD IAPREFIX /0 with a valid OPTION_PD_EXCLUDE using an exclude prefix length of /121 through /128 to trigger the out-of-bounds write and potentially corrupt adjacent stack memory.

dhcpcd Heap Use-After-Free in dhcp6_deprecateaddrs via DHCPv6 RENEW

dhcpcd through 10.3.2, fixed in commit 5733d3c, contains a heap use-after-free vulnerability that allows unauthenticated same-link attackers to crash the daemon by sending a crafted DHCPv6 RENEW reply with RFC6603 OPTION_PD_EXCLUDE and both preferred and valid lifetimes set to zero. Attackers acting as or impersonating a DHCPv6 server can trigger dhcp6_deprecatedele() to free a delegated child address while an outer TAILQ_FOREACH_SAFE iterator in dhcp6_deprecateaddrs() still holds the freed pointer, causing a use-after-free when TAILQ_REMOVE is reached.

dhcpcd before 6.10.0 allows remote attackers to cause a denial of service (invalid read and crash) via vectors related to the option length.

The decode_search function in dhcp.c in dhcpcd 3.x allows remote DHCP servers to cause a denial of service (out-of-bounds write) via a crafted response.

The decode_search function in dhcp.c in dhcpcd 3.x allows remote DHCP servers to cause a denial of service (out-of-bounds read) via a crafted response.

The decode_search function in dhcp.c in dhcpcd 3.x does not properly free allocated memory, which allows remote DHCP servers to cause a denial of service via a crafted response.

The get_option function in dhcpcd 4.0.0 through 6.x before 6.4.3 allows remote DHCP servers to cause a denial of service by resetting the DHO_OPTIONSOVERLOADED option in the (1) bootfile or (2) servername section, which triggers the option to be processed again.

The get_option function in dhcp.c in dhcpcd before 6.2.0, as used in dhcpcd 5.x in Android before 5.1 and other products, does not validate the relationship between length fields and the amount of data, which allows remote DHCP servers to execute arbitrary code or cause a denial of service (memory corruption) via a large length value of an option in a DHCPACK message.

The print_option function in dhcp-common.c in dhcpcd through 6.9.1, as used in dhcp.c in dhcpcd 5.x in Android before 5.1 and other products, misinterprets the return value of the snprintf function, which allows remote DHCP servers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted message.

dhcpcd before 6.10.0, as used in Android 4.x before 4.4.4, 5.0.x before 5.0.2, 5.1.x before 5.1.1, and 6.x before 2016-04-01 and other products, mismanages option lengths, which allows remote attackers to execute arbitrary code or cause a denial of service (heap-based buffer overflow) via a malformed DHCP response, aka internal bug 26461634.

dhcp6.c in dhcpcd before 6.11.7 and 7.x before 7.2.2 has a buffer over-read in the D6_OPTION_PD_EXCLUDE feature.

dhcp.c in dhcpcd before 7.2.1 contains a 1-byte read overflow with DHO_OPTSOVERLOADED.

auth.c in dhcpcd before 7.2.1 allowed attackers to infer secrets by performing latency attacks.

dhcpcd before 7.2.1 contains a buffer overflow in dhcp6_findna in dhcp6.c when reading NA/TA addresses.