From b387d3c1327a3ad2a2509bd3d3491e674392ff21 Mon Sep 17 00:00:00 2001 From: Evgeny Vereshchagin Date: Sat, 29 Sep 2018 03:06:10 +0000 Subject: [PATCH] dhcp6: fix an off-by-one error in dhcp6_option_parse_domainname ==14==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x60200055fa9c at pc 0x0000005458f1 bp 0x7ffc78940d90 sp 0x7ffc78940d88 READ of size 1 at 0x60200055fa9c thread T0 #0 0x5458f0 in dhcp6_option_parse_domainname /work/build/../../src/systemd/src/libsystemd-network/dhcp6-option.c:555:29 #1 0x54706e in dhcp6_lease_set_domains /work/build/../../src/systemd/src/libsystemd-network/sd-dhcp6-lease.c:242:13 #2 0x53fce0 in client_parse_message /work/build/../../src/systemd/src/libsystemd-network/sd-dhcp6-client.c:984:29 #3 0x53f3bc in client_receive_advertise /work/build/../../src/systemd/src/libsystemd-network/sd-dhcp6-client.c:1083:13 #4 0x53d57f in client_receive_message /work/build/../../src/systemd/src/libsystemd-network/sd-dhcp6-client.c:1182:21 #5 0x7f0f7159deee in source_dispatch /work/build/../../src/systemd/src/libsystemd/sd-event/sd-event.c:3042:21 #6 0x7f0f7159d431 in sd_event_dispatch /work/build/../../src/systemd/src/libsystemd/sd-event/sd-event.c:3455:21 #7 0x7f0f7159ea8d in sd_event_run /work/build/../../src/systemd/src/libsystemd/sd-event/sd-event.c:3512:21 #8 0x531f2b in fuzz_client /work/build/../../src/systemd/src/fuzz/fuzz-dhcp6-client.c:44:9 #9 0x531bc1 in LLVMFuzzerTestOneInput /work/build/../../src/systemd/src/fuzz/fuzz-dhcp6-client.c:53:9 #10 0x57bec8 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) /src/libfuzzer/FuzzerLoop.cpp:570:15 #11 0x579d67 in fuzzer::Fuzzer::RunOne(unsigned char const*, unsigned long, bool, fuzzer::InputInfo*, bool*) /src/libfuzzer/FuzzerLoop.cpp:479:3 #12 0x57dc92 in fuzzer::Fuzzer::MutateAndTestOne() /src/libfuzzer/FuzzerLoop.cpp:707:19 #13 0x580ca6 in fuzzer::Fuzzer::Loop(std::__1::vector, std::__1::allocator >, fuzzer::fuzzer_allocator, std::__1::allocator > > > const&) /src/libfuzzer/FuzzerLoop.cpp:838:5 #14 0x55e968 in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) /src/libfuzzer/FuzzerDriver.cpp:764:6 #15 0x551a1c in main /src/libfuzzer/FuzzerMain.cpp:20:10 #16 0x7f0f701a082f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f) #17 0x41e928 in _start (/out/fuzz-dhcp6-client+0x41e928) --- src/libsystemd-network/dhcp6-option.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/libsystemd-network/dhcp6-option.c b/src/libsystemd-network/dhcp6-option.c index 18196b12573..05f589e911c 100644 --- a/src/libsystemd-network/dhcp6-option.c +++ b/src/libsystemd-network/dhcp6-option.c @@ -563,7 +563,7 @@ int dhcp6_option_parse_domainname(const uint8_t *optval, uint16_t optlen, char * /* Literal label */ label = (const char *)&optval[pos]; pos += c; - if (pos > optlen) + if (pos >= optlen) return -EMSGSIZE; if (!GREEDY_REALLOC(ret, allocated, n + !first + DNS_LABEL_ESCAPED_MAX)) {