Re: [libvirt] [PATCH 3/7] nwfilter_ebiptables_driver.c: avoid NULL dereference
Jim Meyering <jim(a)meyering.net> wrote on 04/15/2010 01:36:21 AM:
"Daniel P. Berrange", libvir-list
Stefan Berger wrote:
> libvir-list-bounces(a)redhat.com wrote on 04/14/2010 01:40:17 PM:
>
>> Please respond to "Daniel P. Berrange"
>>
>> On Wed, Apr 14, 2010 at 06:02:32PM +0200, Jim Meyering wrote:
>> > From: Jim Meyering <meyering(a)redhat.com>
[...]
>> > goto tear_down_tmpebchains;
>> >
>> > for (i = 0; i < nruleInstances; i++)
>> > + sa_assert (inst);
>
> Due to this statement here I get segmentation faults for which there
is no
> reason. I have no idea why that is but I have to deactivate this
line for it to
> work again.
> The same is not true for the statement further above... So strange.
How is STATIC_ANALYSIS defined in config.h?
$ grep STATIC_AN config.h
#define STATIC_ANALYSIS 0
Also 0 here.
If it's not 0, then you must have one of these two envvars set:
test -n "$CCC_ANALYZER_ANALYSIS$COVERITY_BUILD_COMMAND" && echo oops
got 'oops' here.
How is sa_assert defined for you?
$ grep -C3 sa_assert src/internal.h
# if STATIC_ANALYSIS
# undef NDEBUG /* Don't let a prior NDEBUG definition cause
trouble. */
# include <assert.h>
# define sa_assert(expr) assert (expr)
# else
# define sa_assert(expr) /* empty */
# endif
With those, the net result in your file should be that
sa_assert is a no-op.
Yes, I agree. My understanding also.
If you're still convinced that the segfault is due to that use
of sa_assert, please send me preprocessed output for that file, i.e.,
cd src
f=nwfilter_ebiptables_driver
touch nwfilter/$f.c
la=libvirt_driver_nwfilter_la
lo=$la-$f.lo
make AM_CPPFLAGS='-E -dD' $lo
mv .libs/$la-$f.o $f.i
The cpp-preprocessed output is now in
src/nwfilter_ebiptables_driver.i
You should be able to see that sa_assert expands to nothing:
$ grep sa_assert $f.i
#define sa_assert(expr)
Well, not quite true. I see the lonely semicolon there that's the
remainder from sa_assert(); -> one would have to write sa_assert(), which
isn't nice, either...
if (ebiptablesExecCLI(&buf, &cli_status) || cli_status != 0)
goto tear_down_tmpebchains;
for (i = 0; i < nruleInstances; i++)
;
switch (inst[i]->ruleType) {
Regards,
Stefan
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