Re: [Tinycc-devel] Small tcc bugs brought to you by american fuzzy lop

[Michael Matz]

H,

On Mon, 30 Jul 2018, John Scott wrote:

> I fuzzed tcc for several hours and found some issues. I'm not familiar
> with tcc's code and can't be of much help in resolving these, but they
> do affect both 0.9.27 and the latest Git version, so I hope to bring
> awareness to these bugs.

Well, in reality it's just a misplaced diagnostic; it's invalid source 
code and tcc rejects it.  But I guess emitting a proper error message 
earlier is nicer.  Fixed in mob, thanks for the report (don't waste too 
much time on fuzzing TCC though; it's generally more useful to test how 
TCC fares on real-world code, not on fuzzed garbage claiming to be C 
code).

> Meanwhile, attempting to preprocess `##include<` in a C source file 
> causes tcc to hang and consume arbitrarily large amounts of memory.

Can't reproduce this with mob, though:
% cat fuzz2.c
##include<
% ./tcc -E fuzz2.c
# 1 "fuzz2.c"
# 1 "/usr/local/lib/tcc/include/" 1
# 1 "fuzz2.c" 2

(using -c works as well, just to be sure).


Ciao,
Michael.