| Summary: | app-forensics/zzuf-0.15 does not fuzz/change any bits for char devices | ||
|---|---|---|---|
| Product: | Gentoo Linux | Reporter: | Marijn Schouten (RETIRED) <hkbst> |
| Component: | Current packages | Assignee: | Sergei Trofimovich (RETIRED) <slyfox> |
| Status: | RESOLVED UPSTREAM | ||
| Severity: | normal | ||
| Priority: | Normal | ||
| Version: | unspecified | ||
| Hardware: | All | ||
| OS: | Linux | ||
| URL: | https://github.com/samhocevar/zzuf/issues/19 | ||
| Whiteboard: | |||
| Package list: | Runtime testing required: | --- | |
|
Description
Marijn Schouten (RETIRED)
2017-03-18 17:43:45 UTC
> zzuf -r0.5 hexdump -vn 128 /dev/zero
Unfortunately zzuf does not handle nicely pipes and char devices.
zzuf assumes ftell() will return sensible thing on FILE* streams
as zzuf does fuzzed/unfuzzed buffer bookkeeping.
Unfortunately fread()/ftell() is not consistent for "/dev/zero"
either (as it's a char device):
$ cat a.c
#include <stdio.h>
int main() {
FILE * f = fopen("/dev/zero", "r");
char b[15];
long o1 = ftell (f);
fread (b, 1, sizeof (b), f);
long o2 = ftell (f);
printf ("advanced at = %lu [%li/%li]\n", o2 - o1, o1, o2);
return 0;
}
$ gcc a.c -o a && ./a
advanced at = 18446744073709551615 [0/-1]
zzuf has a few FIXME around this case:
src/libzzuf/lib-stream.c: /* FIXME: ftell() will return -1 on a pipe such as stdin */ \
src/libzzuf/lib-stream.c: /* FIXME: ftell() will return -1 on a pipe such as stdin */ \
src/libzzuf/lib-stream.c: /* FIXME: ftell() will return -1 on a pipe such as stdin */ \
src/libzzuf/lib-stream.c: /* FIXME: ftell() will return -1 on a pipe such as stdin */ \
I guess tutorial used to work on older libc or kernel.
To workaround it i suggest creating normal file instead of /dev/zero
and use it instead:
$ dd if=/dev/zero of=dz bs=1024 count=100
$ zzuf -r0.5 hexdump -vn 128 dz
0000000 a0c0 b020 40ad c207 148a 1b30 2183 691a
0000010 2811 0705 0030 0170 0843 c862 456d 1ae4
0000020 2161 8362 a196 d782 0bd4 80c4 eb92 281c
0000030 2458 0320 4182 63ee 5028 9741 161c 1229
0000040 2953 2541 27f0 0390 6624 c559 0018 0ba4
0000050 bb50 0a82 1a28 2000 0928 8e04 9228 0a82
0000060 1c44 0440 5a02 62b4 8312 00e5 830b 842c
0000070 4206 8529 01d7 2522 0140 01aa 9119 2644
0000080
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