resolve: avoid memory leak from a partially processed RR
==5==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 4096 byte(s) in 1 object(s) allocated from:
#0 0x4a2056 in __interceptor_malloc /src/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:69:3
#1 0x5180a9 in malloc (/build/fuzz-resource-record+0x5180a9)
#2 0x4f7182 in dns_packet_extend /work/build/../../src/systemd/src/resolve/resolved-dns-packet.c:371:36
#3 0x4f8b8b in dns_packet_append_uint8 /work/build/../../src/systemd/src/resolve/resolved-dns-packet.c:433:13
#4 0x4f8b8b in dns_packet_append_name /work/build/../../src/systemd/src/resolve/resolved-dns-packet.c:597:13
#5 0x4f8f16 in dns_packet_append_key /work/build/../../src/systemd/src/resolve/resolved-dns-packet.c:622:13
#6 0x4fa9a0 in dns_packet_append_rr /work/build/../../src/systemd/src/resolve/resolved-dns-packet.c:883:13
#7 0x4eb00c in dns_resource_record_to_wire_format /work/build/../../src/systemd/src/resolve/resolved-dns-rr.c:1224:13
#8 0x4df7be in LLVMFuzzerTestOneInput /work/build/../../src/systemd/src/resolve/fuzz-resource-record.c:32:16
#9 0x518428 in NaloFuzzerTestOneInput (/build/fuzz-resource-record+0x518428)
#10 0x537433 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:611:15
#11 0x536c1a in fuzzer::Fuzzer::RunOne(unsigned char const*, unsigned long, bool, fuzzer::InputInfo*, bool, bool*) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:514:3
#12 0x5382e9 in fuzzer::Fuzzer::MutateAndTestOne() /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:757:19
#13 0x538fb5 in fuzzer::Fuzzer::Loop(std::__Fuzzer::vector<fuzzer::SizedFile, std::__Fuzzer::allocator<fuzzer::SizedFile> >&) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:895:5
#14 0x52831f in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:912:6
#15 0x528be8 in LLVMFuzzerRunDriver /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:925:10
#16 0x5186a5 in main (/build/fuzz-resource-record+0x5186a5)
#17 0x7f991fab8082 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24082) (BuildId: 1878e6b475720c7c51969e69ab2d276fae6d1dee)
DEDUP_TOKEN: __interceptor_malloc--malloc--dns_packet_extend
SUMMARY: AddressSanitizer: 4096 byte(s) leaked in 1 allocation(s).
Found by Nallocfuzz.
(cherry picked from commit b453ebf1c15935f1ba38fa6775ee26f223e29171)
