| Re: [chrony-dev] Logs from scan-build from Clang 3.4-1 |
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On Thu, Oct 03, 2013 at 03:11:51PM +0200, Paul Menzel wrote:
> using the Clang static analyzer scan-build from Debian Clang version
> 3.4-1, the following warnings are printed.
> /usr/share/clang/scan-build/ccc-analyzer -O2 -g -c regress.c
> regress.c:197:22: warning: The left operand of '<' is a garbage value
> if (((resid[i-1] < 0.0) && (resid[i] < 0.0)) ||
> ~~~~~~~~~~ ^
> regress.c:197:42: warning: The left operand of '<' is a garbage value
> if (((resid[i-1] < 0.0) && (resid[i] < 0.0)) ||
> ~~~~~~~~ ^
> regress.c:198:42: warning: The left operand of '>' is a garbage value
> ((resid[i-1] > 0.0) && (resid[i] > 0.0))) {
> ~~~~~~~~ ^
> regress.c:396:21: warning: The left operand of '>' is a garbage value
> while (x[r] > piv) r--;
> ~~~~ ^
Do you have more information about these? They look like false
positives to me and I think Coverity scan was tripping on them too,
possibly because there are values at negative index with the resid
array.
> /usr/share/clang/scan-build/ccc-analyzer -O2 -g -c cmdmon.c
> cmdmon.c:1940:5: warning: Value stored to 'allowed' is never read
> allowed = 0;
Fixed.
> /usr/share/clang/scan-build/ccc-analyzer -O2 -g -c keys.c
> keys.c:263:7: warning: Function call argument is an uninitialized value
> LOG(LOGS_WARN, LOGF_Keys, "Detected duplicate key %lu", key_id);
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This is a real bug. Fixed.
> /usr/share/clang/scan-build/ccc-analyzer -O2 -g -c manual.c
> manual.c:176:54: warning: The left operand of '*' is a garbage value
> samples[i].residual = offsets[i] - (b0 + agos[i] * b1);
> ~~~~~~~ ^
Not sure about this one.
> /usr/share/clang/scan-build/ccc-analyzer -O2 -g -c cmdparse.c
> acquire.c:623:9: warning: Call to 'malloc' has an allocation size of 0 bytes
> eps = MallocArray(Endpoint, 2*n_sane_sources);
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I don't see a problem here.
> acquire.c:689:54: warning: The left operand of '+' is a garbage value
> estimated_offset = 0.5 * (intervals[index1].lo + intervals[index2].hi);
> ~~~~~~~~~~~~~~~~~~~~ ^
Not sure what's wrong here.
> /usr/share/clang/scan-build/ccc-analyzer -O2 -g -c wrap_adjtimex.c
> sys_linux.c:1164:14: warning: Access to field 'pw_gid' results in a dereference of a null pointer (loaded from variable 'pw')
> if (setgid(pw->pw_gid)) {
> ^~~~~~~~~~
False positive.
> /usr/share/clang/scan-build/ccc-analyzer -O2 -g -c rtc_linux.c
> rtc_linux.c:675:7: warning: Branch condition evaluates to a garbage value
> if (valid) {
> ^~~~~
Another real bug. Fixed.
> /usr/share/clang/scan-build/ccc-analyzer -O2 -g -c getdate.c
> getdate.c:1265:5: warning: Value stored to 'yymsg' is never read
> yymsg = "Deleting";
> ^ ~~~~~~~~~~
This is a file generated by bison.
> scan-build: 16 bugs found.
> scan-build: Run 'scan-view /srv/filme/src/chrony/scan-build/2013-10-03-130043-31884-1' to examine bug reports.
Does that command print more details?
> I suggest to install it on your system yourself, as it also gives nice
> Web pages where the steps are shown how to reach certain conditions.
Unfortunately, Fedora doesn't have llvm-3.4 yet and with 3.3 I get no warnings.
> Unfortunately, I do not know the code well enough to fix certain things,
> so I just posted patches for the easy ones and hope somebody else finds
> the time to address the other warnings.
Thanks for the report!
--
Miroslav Lichvar
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