[llvm-dev] Coverity Scan Needs to be Updated after GitHub Migration

Tom Honermann via llvm-dev
2021-06-11T13:58:50Z

On 6/10/2021 2:54 PM, David Blaikie via llvm-dev wrote:
On Thu, Jun 10, 2021 at 10:42 AM Mehdi AMINI <joker.eph at
gmail.com<mailto:joker.eph at gmail.com>> wrote:



On Thu, Jun 10, 2021 at 10:20 AM David Blaikie via llvm-dev <llvm-dev at
lists.llvm.org<mailto:llvm-dev at lists.llvm.org>> wrote:

From Coverity:

Please find the latest report on new defect(s) introduced to llvm found with
Coverity Scan.

8 new defect(s) introduced to llvm found with Coverity Scan.
19 defect(s), reported by Coverity Scan earlier, were marked fixed in the recent
build analyzed by Coverity Scan.

New defect(s) Reported-by: Coverity Scan
Showing 8 of 8 defect(s)


** CID 1457502:  Uninitialized members  (UNINIT_CTOR)
/lld/MachO/InputSection.h: 109 in lld::macho::StringPiece::StringPiece(unsigned
long, unsigned int)()

Is it easy for us to disable low-value findings (both on a per-instance, but
also per-check-tye) basis in source (ie: without having to modify an external
config)?

Source annotations are available for suppressing per-instance issues, but no
source annotations are available to disable checkers entirely.

I don't see an option for disabling specific checkers in Coverity Scan.
Checker enable/disable and tuning options are available when using a Coverity
installation.  I don't know why those capabilities wouldn't be exposed
to Coverity Scan users.

For instance, I'm not sure it's valuable for us to get notification on
any member not initialized by a ctor. That could readily be detected by
clang-tidy or clang warnings and we don't implement such checks in those
places (which would be higher value because they can find the issue sooner
rather than waiting for a long-running static analysis to come back with
results).

Keeping the warnings low-noise would be really important (so whoever set this up
or requested it I hope is really pushing to reduce the noise until nearly all
results have pretty broad agreement that they should be fixed).

Yes, the general deployment recommendation is to tune to minimize FPs and low
value results and then relax such tuning as issues are addressed.

Tom.




________________________________________________________________________________________________________
*** CID 1457502:  Uninitialized members  (UNINIT_CTOR)
/lld/MachO/InputSection.h: 109 in lld::macho::StringPiece::StringPiece(unsigned
long, unsigned int)()
103       // Offset from the start of the containing input section.
104       uint32_t inSecOff;
105       uint32_t hash;
106       // Offset from the start of the containing output section.
107       uint64_t outSecOff;
108
>>>     CID 1457502:  Uninitialized members  (UNINIT_CTOR)
>>>     Non-static class member "outSecOff" is not
initialized in this constructor nor in any functions that it calls.
109       StringPiece(uint64_t off, uint32_t hash) : inSecOff(off), hash(hash)
{}
110     };
111
112     // CStringInputSections are composed of multiple null-terminated string
113     // literals, which we represent using StringPieces. These literals can
be
114     // deduplicated and tail-merged, so translating offsets between the
input and

** CID 1457501:  Uninitialized members  (UNINIT_CTOR)
/llvm/lib/ObjectYAML/XCOFFEmitter.cpp: 36 in
<unnamed>::XCOFFWriter::XCOFFWriter(llvm::XCOFFYAML::Object &,
llvm::raw_ostream &, llvm::function_ref<void (const llvm::Twine
&)>)()


________________________________________________________________________________________________________
*** CID 1457501:  Uninitialized members  (UNINIT_CTOR)
/llvm/lib/ObjectYAML/XCOFFEmitter.cpp: 36 in
<unnamed>::XCOFFWriter::XCOFFWriter(llvm::XCOFFYAML::Object &,
llvm::raw_ostream &, llvm::function_ref<void (const llvm::Twine
&)>)()
30
31     class XCOFFWriter {
32     public:
33       XCOFFWriter(XCOFFYAML::Object &Obj, raw_ostream &OS,
yaml::ErrorHandler EH)
34           : Obj(Obj), W(OS, support::big), ErrHandler(EH) {
35         Is64Bit = Obj.Header.Magic ==
(llvm::yaml::Hex16)XCOFF::XCOFF64;
>>>     CID 1457501:  Uninitialized members  (UNINIT_CTOR)
>>>     Non-static class member "StartOffset" is not
initialized in this constructor nor in any functions that it calls.
36       }
37       bool writeXCOFF();
38
39     private:
40       bool initFileHeader(uint64_t CurrentOffset);
41       bool initSectionHeader(uint64_t &CurrentOffset);

** CID 1457500:  Incorrect expression  (SIZEOF_MISMATCH)
/compiler-rt/lib/dfsan/dfsan_custom.cpp: 2367 in format_buffer(char *, unsigned
long, const char *, unsigned char *, unsigned char *, unsigned int *, unsigned
int *, __va_list_tag *)()


________________________________________________________________________________________________________
*** CID 1457500:  Incorrect expression  (SIZEOF_MISMATCH)
/compiler-rt/lib/dfsan/dfsan_custom.cpp: 2367 in format_buffer(char *, unsigned
long, const char *, unsigned char *, unsigned char *, unsigned int *, unsigned
int *, __va_list_tag *)()
2361             case 'n': {
2362               int *ptr = va_arg(ap, int *);
2363               *ptr = (int)formatter.str_off;
2364               va_labels++;
2365               if (va_origins)
2366                 va_origins++;
>>>     CID 1457500:  Incorrect expression  (SIZEOF_MISMATCH)
>>>     Passing argument "ptr" of type "int *" and
argument "8UL /* sizeof (ptr) */" to function
"dfsan_set_label" is suspicious.
2367               dfsan_set_label(0, ptr, sizeof(ptr));

I think clang has a sizeof warning for things like memcpy, right? I wonder if
this more broad warning provides a lot of value, or not?

2368               end_fmt = true;
2369               break;
2370             }
2371
2372             case '%':

** CID 1457499:  Incorrect expression  (DIVIDE_BY_ZERO)
/llvm/lib/Analysis/CFGPrinter.cpp: 308 in
llvm::DOTGraphTraits<llvm::DOTFuncInfo *>::isNodeHidden(const
llvm::BasicBlock *, const llvm::DOTFuncInfo *)()


________________________________________________________________________________________________________
*** CID 1457499:  Incorrect expression  (DIVIDE_BY_ZERO)
/llvm/lib/Analysis/CFGPrinter.cpp: 308 in
llvm::DOTGraphTraits<llvm::DOTFuncInfo *>::isNodeHidden(const
llvm::BasicBlock *, const llvm::DOTFuncInfo *)()
302                                                      const DOTFuncInfo
*CFGInfo) {
303       if (HideColdPaths.getNumOccurrences() > 0)
304         if (auto *BFI = CFGInfo->getBFI()) {
305           uint64_t NodeFreq = BFI->getBlockFreq(Node).getFrequency();
306           uint64_t EntryFreq = BFI->getEntryFreq();
307           // Hide blocks with relative frequency below HideColdPaths
threshold.
>>>     CID 1457499:  Incorrect expression  (DIVIDE_BY_ZERO)
>>>     In expression "(double)NodeFreq / EntryFreq",
division by expression "EntryFreq" which may be zero has undefined
behavior.
308           if ((double)NodeFreq / EntryFreq < HideColdPaths)
309             return true;
310         }
311       if (HideUnreachablePaths || HideDeoptimizePaths) {
312         if (isOnDeoptOrUnreachablePath.find(Node) =313
isOnDeoptOrUnreachablePath.end())

** CID 1457498:    (DEADCODE)
/clang/lib/Sema/SemaDeclCXX.cpp: 11843 in
clang::Sema::CheckUsingShadowDecl(clang::BaseUsingDecl *, clang::NamedDecl *,
const clang::LookupResult &, clang::UsingShadowDecl *&)()
/clang/lib/Sema/SemaDeclCXX.cpp: 11789 in
clang::Sema::CheckUsingShadowDecl(clang::BaseUsingDecl *, clang::NamedDecl *,
const clang::LookupResult &, clang::UsingShadowDecl *&)()


________________________________________________________________________________________________________
*** CID 1457498:    (DEADCODE)
/clang/lib/Sema/SemaDeclCXX.cpp: 11843 in
clang::Sema::CheckUsingShadowDecl(clang::BaseUsingDecl *, clang::NamedDecl *,
const clang::LookupResult &, clang::UsingShadowDecl *&)()
11837         return true;
11838       }
11839
11840       // No conflict between a tag and a non-tag.
11841       if (!NonTag) return false;
11842
>>>     CID 1457498:    (DEADCODE)
>>>     Execution cannot reach this statement: "<temporary>
= this->Diag(cl...".
11843       Diag(BUD->getLocation(), diag::err_using_decl_conflict);
11844       Diag(Target->getLocation(), diag::note_using_decl_target);
11845       Diag(NonTag->getLocation(), diag::note_using_decl_conflict);
11846       BUD->setInvalidDecl();
11847       return true;
11848     }
/clang/lib/Sema/SemaDeclCXX.cpp: 11789 in
clang::Sema::CheckUsingShadowDecl(clang::BaseUsingDecl *, clang::NamedDecl *,
const clang::LookupResult &, clang::UsingShadowDecl *&)()
11783       // Always emit a diagnostic for a mismatch between an unresolved
11784       // using_if_exists and a resolved using declaration in either
direction.
11785       if (isa<UnresolvedUsingIfExistsDecl>(Target) !11786
(isa_and_nonnull<UnresolvedUsingIfExistsDecl>(NonTag))) {
11787         if (!NonTag && !Tag)
11788           return false;
>>>     CID 1457498:    (DEADCODE)
>>>     Execution cannot reach this statement: "<temporary>
= this->Diag(cl...".
11789         Diag(BUD->getLocation(), diag::err_using_decl_conflict);
11790         Diag(Target->getLocation(), diag::note_using_decl_target);
11791         Diag((NonTag ? NonTag : Tag)->getLocation(),
11792              diag::note_using_decl_conflict);
11793         BUD->setInvalidDecl();
11794         return true;

** CID 1457497:  Integer handling issues  (NEGATIVE_RETURNS)


________________________________________________________________________________________________________
*** CID 1457497:  Integer handling issues  (NEGATIVE_RETURNS)
/lld/MachO/InputSection.cpp: 117 in
lld::macho::CStringInputSection::getStringPiece(unsigned long) const()
111     const StringPiece &CStringInputSection::getStringPiece(uint64_t off)
const {
112       if (off >= data.size())
113         fatal(toString(this) + ": offset is outside the section");
114
115       auto it 116           partition_point(pieces, [=](StringPiece p) {
return p.inSecOff <= off; });
>>>     CID 1457497:  Integer handling issues  (NEGATIVE_RETURNS)
>>>     A negative constant "-1L" is passed as an argument to
a parameter that cannot be negative.

Doesn't sound correct - negatively indexing from an iterator is valid, I
believe? (though perhaps this check is using some info about the nature of
`partition_point` being able to return the begin iterator)

117       return it[-1];
118     }
119
120     uint64_t CStringInputSection::getFileOffset(uint64_t off) const {
121       return parent->fileOff + getOffset(off);
122     }

** CID 1457496:  Possible Control flow issues  (DEADCODE)
/clang/lib/Sema/SemaDeclCXX.cpp: 11833 in
clang::Sema::CheckUsingShadowDecl(clang::BaseUsingDecl *, clang::NamedDecl *,
const clang::LookupResult &, clang::UsingShadowDecl *&)()


________________________________________________________________________________________________________
*** CID 1457496:  Possible Control flow issues  (DEADCODE)
/clang/lib/Sema/SemaDeclCXX.cpp: 11833 in
clang::Sema::CheckUsingShadowDecl(clang::BaseUsingDecl *, clang::NamedDecl *,
const clang::LookupResult &, clang::UsingShadowDecl *&)()
11827       // Target is not a function.
11828
11829       if (isa<TagDecl>(Target)) {
11830         // No conflict between a tag and a non-tag.
11831         if (!Tag) return false;
11832
>>>     CID 1457496:  Possible Control flow issues  (DEADCODE)
>>>     Execution cannot reach this statement: "<temporary>
= this->Diag(cl...".
11833         Diag(BUD->getLocation(), diag::err_using_decl_conflict);
11834         Diag(Target->getLocation(), diag::note_using_decl_target);
11835         Diag(Tag->getLocation(), diag::note_using_decl_conflict);
11836         BUD->setInvalidDecl();
11837         return true;
11838       }

** CID 1419078:  Resource leaks  (VIRTUAL_DTOR)
/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp: 541 in ()


________________________________________________________________________________________________________
*** CID 1419078:  Resource leaks  (VIRTUAL_DTOR)
/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp: 541 in ()
535         return (Twine(Removed ? "-" : " ") + (InMST ?
" " : "*") +
536                 (IsCritical ? "c" : " ") + "
W=" + Twine(Weight)).str();
537       }
538     };
539
540     // This class stores the auxiliary information for each
BB.
>>>     CID 1419078:  Resource leaks  (VIRTUAL_DTOR)
>>>     Class "<unnamed>::BBInfo" does not have a
virtual destructor.
541     struct BBInfo {
542       BBInfo *Group;
543       uint32_t Index;
544       uint32_t Rank = 0;
545
546       BBInfo(unsigned IX) : Group(this), Index(IX) {}


________________________________________________________________________________________________________
To view the defects in Coverity Scan visit,
https://u15810271.ct.sendgrid.net/ls/click?upn=HRESupC-2F2Czv4BOaCWWCy7my0P0qcxCbhZ31OYv50yqtGMuad6pPsL7inW23sAqZCWZD0rQ5FZsyk18zSjnBpg-3D-3Dqen7_nlj59xHPRAo5NMSpMZh-2B1UYnQ4IBJNE2FCxtFGv5-2FfRZ2ZNTfin-2BJg3vqHM-2BrKWO-2BwAgQVf1GGFXh4xVX9UzXjq3jPiI59xzjIzanRxv0XSIVZFqDyJd-2BdQm4cXqcdS7Dt0L1fNQpWyw15e-2BbU4YMt1YpKZVa4kbM7Bjl6hGDatG6tnUuz5zUAdmlq-2B7z2QmYSc2DTghseWofWoq-2Bn7ssA-3D-3D<https://urldefense.com/v3/__https://u15810271.ct.sendgrid.net/ls/click?upn=HRESupC-2F2Czv4BOaCWWCy7my0P0qcxCbhZ31OYv50yqtGMuad6pPsL7inW23sAqZCWZD0rQ5FZsyk18zSjnBpg-3D-3Dqen7_nlj59xHPRAo5NMSpMZh-2B1UYnQ4IBJNE2FCxtFGv5-2FfRZ2ZNTfin-2BJg3vqHM-2BrKWO-2BwAgQVf1GGFXh4xVX9UzXjq3jPiI59xzjIzanRxv0XSIVZFqDyJd-2BdQm4cXqcdS7Dt0L1fNQpWyw15e-2BbU4YMt1YpKZVa4kbM7Bjl6hGDatG6tnUuz5zUAdmlq-2B7z2QmYSc2DTghseWofWoq-2Bn7ssA-3D-3D__;!!A4F2R9G_pg!PQwy8rAjiKMI_cBfDwnfPHyGD0k6TmR-QczpyNJJYgHISD-Qk1-6wPLjy535GVbE$>

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On Thu, Jun 10, 2021 at 7:37 AM Luke Benes via llvm-dev <llvm-dev at
lists.llvm.org<mailto:llvm-dev at lists.llvm.org>>
wrote:
> https://scan.coverity.com/projects/llvm
> Should run once a day.

Sylvester,
The report seems to be working perfectly. Thank you for taking the time to get
this up and running again!

My only concern is that there is no visibly on these reports. Without the new
issues being reported here, it is highly unlikely that they will get addressed.

Since there was interest and no objections, could you please add the [llvm-dev]
list to the email?

You can do this by going to the "Project Settings" page:
https://scan.coverity.com/projects/llvm?tab=project_settings

"Additional Emails for New Defect Notifications"
-> llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>

Then could you please lower the report frequency to once or twice a week? With
that we will receive weekly reports like this:

http://document-foundation-mail-archive.969070.n3.nabble.com/New-Defects-reported-by-Coverity-Scan-for-LibreOffice-td4301203.html<https://urldefense.com/v3/__http://document-foundation-mail-archive.969070.n3.nabble.com/New-Defects-reported-by-Coverity-Scan-for-LibreOffice-td4301203.html__;!!A4F2R9G_pg!PQwy8rAjiKMI_cBfDwnfPHyGD0k6TmR-QczpyNJJYgHISD-Qk1-6wPLjy7OhpJPm$>

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