Fix invalid memory access #1596
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We can access `flow->protos` union only after checking the protocol.
Checking `flow->detected_protocol.master_protocol` is redundant because
we already check it in `is_ndpi_proto`
```
AddressSanitizer:DEADLYSIGNAL
=================================================================
==29739==ERROR: AddressSanitizer: SEGV on unknown address 0x000000353820 (pc 0x7f9b64dd2717 bp 0x7fff161a52f0 sp 0x7fff161a4aa8 T0)
==29739==The signal is caused by a READ memory access.
#0 0x7f9b64dd2717 /build/glibc-SzIz7B/glibc-2.31/string/../sysdeps/x86_64/multiarch/strlen-avx2.S:96
ntop#1 0x555c65e597d8 in __interceptor_strlen (/home/ivan/svnrepos/nDPI/fuzz/fuzz_ndpi_reader_with_main+0x6407d8) (BuildId: 11ac8ec30f1d49fb0276c9b03368e491505d2bba)
ntop#2 0x555c65fd85fa in ndpi_strdup /home/ivan/svnrepos/nDPI/src/lib/ndpi_main.c:269:13
ntop#3 0x555c65f3e8c6 in process_ndpi_collected_info /home/ivan/svnrepos/nDPI/example/reader_util.c:1188:36
ntop#4 0x555c65f52cab in packet_processing /home/ivan/svnrepos/nDPI/example/reader_util.c:1567:2
ntop#5 0x555c65f4b632 in ndpi_workflow_process_packet /home/ivan/svnrepos/nDPI/example/reader_util.c:2110:10
ntop#6 0x555c65f04d29 in LLVMFuzzerTestOneInput /home/ivan/svnrepos/nDPI/fuzz/fuzz_ndpi_reader.c:109:7
ntop#7 0x555c65f054bb in main /home/ivan/svnrepos/nDPI/fuzz/fuzz_ndpi_reader.c:181:17
ntop#8 0x7f9b64c6e082 in __libc_start_main /build/glibc-SzIz7B/glibc-2.31/csu/../csu/libc-start.c:308:16
ntop#9 0x555c65e4253d in _start (/home/ivan/svnrepos/nDPI/fuzz/fuzz_ndpi_reader_with_main+0x62953d) (BuildId: 11ac8ec30f1d49fb0276c9b03368e491505d2bba)
```
Found by oss-fuzzer.
See: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=48020
|
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utoni
approved these changes
Jun 14, 2022
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We can access
flow->protosunion only after checking the protocol.Checking
flow->detected_protocol.master_protocolis redundant becausewe already check it in
is_ndpi_protoFound by oss-fuzzer.
See: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=48020