Netwide Assembler (NASM) 2.14rc15 has a buffer over-read in x86/regflags.c.
An buffer overflow trigger upon fuzzing. We compiled the program with ASAN to see the result crash. Target version nasm-2.14rc15. The issue found by AFL. ASAN output:
==17458==ERROR: AddressSanitizer: global-buffer-overflow on address 0x0000008d8090 at pc 0x00000056d272 bp 0x7ffe65d7d2d0 sp 0x7ffe65d7d2c8
READ of size 8 at 0x0000008d8090 thread T0
#0 0x56d271 (/home/john/fuzzing/nasm-2.14rc15/nasm+0x56d271)
#1 0x50e027 (/home/john/fuzzing/nasm-2.14rc15/nasm+0x50e027)
#2 0x7f8a4f7deb96 (/lib/x86_64-linux-gnu/libc.so.6+0x21b96)
#3 0x41cac9 (/home/john/fuzzing/nasm-2.14rc15/nasm+0x41cac9)
0x0000008d8090 is located 8 bytes to the right of global variable 'nasm_reg_flags' defined in 'x86/regflags.c:6:17' (0x8d7900) of size 1928
SUMMARY: AddressSanitizer: global-buffer-overflow (/home/john/fuzzing/nasm-2.14rc15/nasm+0x56d271)
Shadow bytes around the buggy address:
0x000080112fc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x000080112fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x000080112fe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x000080112ff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x000080113000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x000080113010: 00 f9[f9]f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
0x000080113020: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
0x000080113030: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
0x000080113040: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
0x000080113050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x000080113060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
Left alloca redzone: ca
Right alloca redzone: cb
==17458==ABORTING