A NULL pointer dereference in the function if_condition() modules/preprocs/nasm/nasm-pp.c:2134

[Clingto]

System info:
Ubuntu 16.04.6 LTS, X64, gcc 5.4.0, yasm (latest master 009450c)
Compile Command:

$ ./autogen.sh
make distclean

CC=gcc CXX=g++ CFLAGS="-fsanitize=address -fno-omit-frame-pointer -g" CXXFLAGS="-fsanitize=address -fno-omit-frame-pointer -g" ./configure --prefix=$PWD/build --disable-shared
make -j
make install

Run Command:

$ yasm  $POC

POC file:
https://github.com/Clingto/POC/blob/master/MSA/yasm/yasm-2134-if_condition-null-pointer-deref

ASAN info:

ASAN:SIGSEGV
=================================================================
==13685==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x7f1a02e5e870 bp 0x7fffcb38b530 sp 0x7fffcb38b380 T0)
    #0 0x7f1a02e5e86f in if_condition  test/yasm-uaf/SRC_asan/modules/preprocs/nasm/nasm-pp.c:2134
    #1 0x7f1a02eb88c7 in do_directive  test/yasm-uaf/SRC_asan/modules/preprocs/nasm/nasm-pp.c:2907
    #2 0x7f1a02ec0333 in pp_getline  test/yasm-uaf/SRC_asan/modules/preprocs/nasm/nasm-pp.c:5083
    #3 0x7f1a02ea9d46 in nasm_preproc_get_line  test/yasm-uaf/SRC_asan/modules/preprocs/nasm/nasm-preproc.c:198
    #4 0x7f1a02e9b2ac in nasm_parser_parse  test/yasm-uaf/SRC_asan/modules/parsers/nasm/nasm-parse.c:218
    #5 0x7f1a02e8f36b in nasm_do_parse  test/yasm-uaf/SRC_asan/modules/parsers/nasm/nasm-parser.c:66
    #6 0x7f1a02e8f36b in nasm_parser_do_parse  test/yasm-uaf/SRC_asan/modules/parsers/nasm/nasm-parser.c:83
    #7 0x402c84 in do_assemble  test/yasm-uaf/SRC_asan/frontends/yasm/yasm.c:521
    #8 0x402c84 in main  test/yasm-uaf/SRC_asan/frontends/yasm/yasm.c:753
    #9 0x7f1a0603682f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
    #10 0x403ee8 in _start ( test/yasm-uaf/bin_asan/bin/yasm+0x403ee8)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV  test/yasm-uaf/SRC_asan/modules/preprocs/nasm/nasm-pp.c:2134 if_condition
==13685==ABORTING

[rathann]

This was assigned CVE-2021-33460 .