Paul Eggert wrote:
> > Paul Eggert wrote:
> >> * lib/getopt.c (process_long_option): Simplify logic slightly.
> >> This pacifies gcc -flto -Wanalyzer-null-dereference when compiling
> >> GNU tar on x86-64 with gcc 13.2.1 20231205 (Red Hat 13.2.1-6).
> > This appears to trade a false alarm for another false alarm. Namely,
> > now Coverity reports:
> >
> > 270 }
> > 271 if (ambig_set)
> >>>> CID 1574557: Memory - corruptions (ARRAY_VS_SINGLETON)
> >>>> Using "ambig_set" as an array. This might corrupt or misinterpret
> >>>> adjacent memory locations.
> > 272 ambig_set[option_index] = 1;
> >
> > I guess we can ignore it?
>
> Yes, let's do that. We're already ignoring what must be hundreds of
> Coverity false positives, and there's little harm in ignoring one more.
Unfortunately, this wasn't a false alarm, but a good alarm.
Namely, I see the 'test-getopt-gnu' test fail (via abort()) on
- Linux/x86_64 with clang+asan+ubsan,
- OpenBSD 7.2/sparc64,
and crash (via SIGSEGV) on
- FreeBSD 14.0/powerpc64.
Debugging it with clang+asan+ubsan, it gets an out-of-bounds access
here:
if (ambig_set && ambig_set != &ambig_fallback)
ambig_set[option_index] = 1; // <===
getopt.c line 272
}
with these local variables:
(gdb) info locals
ambig_set = 0x7ffff5c001a0 ""
ambig_fallback = 0 '\000'
ambig_malloced = 0x0
indfound = 4
nameend = 0x55555576c243 <str+3> ""
namelen = 1
p = 0x555555794b60 <long_options_required+160>
pfound = 0x555555794b40 <long_options_required+128>
n_options = 8
option_index = 5
(gdb) print ambig_set == &ambig_fallback
$5 = 1
This patch fixes it.
2024-01-17 Bruno Haible <br...@clisp.org>
getopt-gnu: Fix out-of-bounds access (regression 2023-12-11).
* lib/getopt.c (process_long_option): Don't set ambig_set[option_index]
if ambig_set is &ambig_fallback.
diff --git a/lib/getopt.c b/lib/getopt.c
index 928306304e..f66f119ec5 100644
--- a/lib/getopt.c
+++ b/lib/getopt.c
@@ -268,7 +268,7 @@ process_long_option (int argc, char **argv, const char
*optstring,
ambig_set[indfound] = 1;
}
}
- if (ambig_set)
+ if (ambig_set && ambig_set != &ambig_fallback)
ambig_set[option_index] = 1;
}
}
