r337470 - [Sema] Add a new warning, -Wmemset-transposed-args
Nico Weber via cfe-commits
cfe-commits at lists.llvm.org
Sat Jul 21 13:33:12 PDT 2018
This has a false positive on ffmpeg:
../../third_party/ffmpeg/libavcodec/options.c:273:64: error: 'size'
argument to memset is '0'; did you mean to transpose the last two
arguments? [-Werror,-Wmemset-transposed-args]
alloc_and_copy_or_fail(intra_matrix, 64 * sizeof(int16_t), 0);
With:
#define alloc_and_copy_or_fail(obj, size, pad) \
if (src->obj && size > 0) { \
dest->obj = av_malloc(size + pad); \
if (!dest->obj) \
goto fail; \
memcpy(dest->obj, src->obj, size); \
if (pad) \
memset(((uint8_t *) dest->obj) + size, 0, pad); \
}
(
https://cs.chromium.org/chromium/src/third_party/ffmpeg/libavcodec/options.c?q=alloc_and_copy_or_fail&sq=package:chromium&g=0&l=261
; https://bugs.chromium.org/p/chromium/issues/detail?id=866202)
Maybe the warning shouldn't fire if the memset is from a macro?
On Thu, Jul 19, 2018 at 12:51 PM Erik Pilkington via cfe-commits <
cfe-commits at lists.llvm.org> wrote:
> Author: epilk
> Date: Thu Jul 19 09:46:15 2018
> New Revision: 337470
>
> URL: http://llvm.org/viewvc/llvm-project?rev=337470&view=rev
> Log:
> [Sema] Add a new warning, -Wmemset-transposed-args
>
> This diagnoses calls to memset that have the second and third arguments
> transposed, for example:
>
> memset(buf, sizeof(buf), 0);
>
> This is done by checking if the third argument is a literal 0, or if the
> second
> is a sizeof expression (and the third isn't). The first check is also done
> for
> calls to bzero.
>
> Differential revision: https://reviews.llvm.org/D49112
>
> Added:
> cfe/trunk/test/Sema/transpose-memset.c
> Modified:
> cfe/trunk/include/clang/Basic/DiagnosticGroups.td
> cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
> cfe/trunk/lib/Sema/SemaChecking.cpp
>
> Modified: cfe/trunk/include/clang/Basic/DiagnosticGroups.td
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticGroups.td?rev=337470&r1=337469&r2=337470&view=diff
>
> ==============================================================================
> --- cfe/trunk/include/clang/Basic/DiagnosticGroups.td (original)
> +++ cfe/trunk/include/clang/Basic/DiagnosticGroups.td Thu Jul 19 09:46:15
> 2018
> @@ -443,6 +443,13 @@ def : DiagGroup<"synth">;
> def SizeofArrayArgument : DiagGroup<"sizeof-array-argument">;
> def SizeofArrayDecay : DiagGroup<"sizeof-array-decay">;
> def SizeofPointerMemaccess : DiagGroup<"sizeof-pointer-memaccess">;
> +def MemsetTransposedArgs : DiagGroup<"memset-transposed-args">;
> +def DynamicClassMemaccess : DiagGroup<"dynamic-class-memaccess">;
> +def NonTrivialMemaccess : DiagGroup<"nontrivial-memaccess">;
> +def SuspiciousBzero : DiagGroup<"suspicious-bzero">;
> +def SuspiciousMemaccess : DiagGroup<"suspicious-memaccess",
> + [SizeofPointerMemaccess, DynamicClassMemaccess,
> + NonTrivialMemaccess, MemsetTransposedArgs, SuspiciousBzero]>;
> def StaticInInline : DiagGroup<"static-in-inline">;
> def StaticLocalInInline : DiagGroup<"static-local-in-inline">;
> def GNUStaticFloatInit : DiagGroup<"gnu-static-float-init">;
>
> Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=337470&r1=337469&r2=337470&view=diff
>
> ==============================================================================
> --- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
> +++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Thu Jul 19
> 09:46:15 2018
> @@ -619,14 +619,14 @@ def warn_cstruct_memaccess : Warning<
> "%select{destination for|source of|first operand of|second operand of}0
> this "
> "%1 call is a pointer to record %2 that is not trivial to "
> "%select{primitive-default-initialize|primitive-copy}3">,
> - InGroup<DiagGroup<"nontrivial-memaccess">>;
> + InGroup<NonTrivialMemaccess>;
> def note_nontrivial_field : Note<
> "field is non-trivial to %select{copy|default-initialize}0">;
> def warn_dyn_class_memaccess : Warning<
> "%select{destination for|source of|first operand of|second operand of}0
> this "
> "%1 call is a pointer to %select{|class containing a }2dynamic class
> %3; "
> "vtable pointer will be %select{overwritten|copied|moved|compared}4">,
> - InGroup<DiagGroup<"dynamic-class-memaccess">>;
> + InGroup<DynamicClassMemaccess>;
> def note_bad_memaccess_silence : Note<
> "explicitly cast the pointer to silence this warning">;
> def warn_sizeof_pointer_expr_memaccess : Warning<
> @@ -655,7 +655,19 @@ def note_memsize_comparison_paren : Note
> "did you mean to compare the result of %0 instead?">;
> def note_memsize_comparison_cast_silence : Note<
> "explicitly cast the argument to size_t to silence this warning">;
> -
> +def warn_suspicious_sizeof_memset : Warning<
> + "%select{'size' argument to memset is '0'|"
> + "setting buffer to a 'sizeof' expression}0"
> + "; did you mean to transpose the last two arguments?">,
> + InGroup<MemsetTransposedArgs>;
> +def note_suspicious_sizeof_memset_silence : Note<
> + "%select{parenthesize the third argument|"
> + "cast the second argument to 'int'}0 to silence">;
> +def warn_suspicious_bzero_size : Warning<"'size' argument to bzero is
> '0'">,
> + InGroup<SuspiciousBzero>;
> +def note_suspicious_bzero_size_silence : Note<
> + "parenthesize the second argument to silence">;
> +
> def warn_strncat_large_size : Warning<
> "the value of the size argument in 'strncat' is too large, might lead
> to a "
> "buffer overflow">, InGroup<StrncatSize>;
>
> Modified: cfe/trunk/lib/Sema/SemaChecking.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=337470&r1=337469&r2=337470&view=diff
>
> ==============================================================================
> --- cfe/trunk/lib/Sema/SemaChecking.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaChecking.cpp Thu Jul 19 09:46:15 2018
> @@ -8629,24 +8629,26 @@ static const CXXRecordDecl *getContained
> return nullptr;
> }
>
> +static const UnaryExprOrTypeTraitExpr *getAsSizeOfExpr(const Expr *E) {
> + if (const auto *Unary = dyn_cast<UnaryExprOrTypeTraitExpr>(E))
> + if (Unary->getKind() == UETT_SizeOf)
> + return Unary;
> + return nullptr;
> +}
> +
> /// If E is a sizeof expression, returns its argument expression,
> /// otherwise returns NULL.
> static const Expr *getSizeOfExprArg(const Expr *E) {
> - if (const UnaryExprOrTypeTraitExpr *SizeOf =
> - dyn_cast<UnaryExprOrTypeTraitExpr>(E))
> - if (SizeOf->getKind() == UETT_SizeOf && !SizeOf->isArgumentType())
> + if (const UnaryExprOrTypeTraitExpr *SizeOf = getAsSizeOfExpr(E))
> + if (!SizeOf->isArgumentType())
> return SizeOf->getArgumentExpr()->IgnoreParenImpCasts();
> -
> return nullptr;
> }
>
> /// If E is a sizeof expression, returns its argument type.
> static QualType getSizeOfArgType(const Expr *E) {
> - if (const UnaryExprOrTypeTraitExpr *SizeOf =
> - dyn_cast<UnaryExprOrTypeTraitExpr>(E))
> - if (SizeOf->getKind() == UETT_SizeOf)
> - return SizeOf->getTypeOfArgument();
> -
> + if (const UnaryExprOrTypeTraitExpr *SizeOf = getAsSizeOfExpr(E))
> + return SizeOf->getTypeOfArgument();
> return QualType();
> }
>
> @@ -8742,6 +8744,86 @@ struct SearchNonTrivialToCopyField
>
> }
>
> +/// Detect if \c SizeofExpr is likely to calculate the sizeof an object.
> +static bool doesExprLikelyComputeSize(const Expr *SizeofExpr) {
> + SizeofExpr = SizeofExpr->IgnoreParenImpCasts();
> +
> + if (const auto *BO = dyn_cast<BinaryOperator>(SizeofExpr)) {
> + if (BO->getOpcode() != BO_Mul && BO->getOpcode() != BO_Add)
> + return false;
> +
> + return doesExprLikelyComputeSize(BO->getLHS()) ||
> + doesExprLikelyComputeSize(BO->getRHS());
> + }
> +
> + return getAsSizeOfExpr(SizeofExpr) != nullptr;
> +}
> +
> +/// Check if the ArgLoc originated from a macro passed to the call at
> CallLoc.
> +///
> +/// \code
> +/// #define MACRO 0
> +/// foo(MACRO);
> +/// foo(0);
> +/// \endcode
> +///
> +/// This should return true for the first call to foo, but not for the
> second
> +/// (regardless of whether foo is a macro or function).
> +static bool isArgumentExpandedFromMacro(SourceManager &SM,
> + SourceLocation CallLoc,
> + SourceLocation ArgLoc) {
> + if (!CallLoc.isMacroID())
> + return SM.getFileID(CallLoc) != SM.getFileID(ArgLoc);
> +
> + return SM.getFileID(SM.getImmediateMacroCallerLoc(CallLoc)) !=
> + SM.getFileID(SM.getImmediateMacroCallerLoc(ArgLoc));
> +}
> +
> +/// Diagnose cases like 'memset(buf, sizeof(buf), 0)', which should have
> the
> +/// last two arguments transposed.
> +static void CheckMemaccessSize(Sema &S, unsigned BId, const CallExpr
> *Call) {
> + if (BId != Builtin::BImemset && BId != Builtin::BIbzero)
> + return;
> +
> + const Expr *SizeArg =
> + Call->getArg(BId == Builtin::BImemset ? 2 : 1)->IgnoreImpCasts();
> +
> + // If we're memsetting or bzeroing 0 bytes, then this is likely an
> error.
> + SourceLocation CallLoc = Call->getRParenLoc();
> + SourceManager &SM = S.getSourceManager();
> + if (isa<IntegerLiteral>(SizeArg) &&
> + cast<IntegerLiteral>(SizeArg)->getValue() == 0 &&
> + !isArgumentExpandedFromMacro(SM, CallLoc, SizeArg->getExprLoc())) {
> +
> + SourceLocation DiagLoc = SizeArg->getExprLoc();
> +
> + // Some platforms #define bzero to __builtin_memset. See if this is
> the
> + // case, and if so, emit a better diagnostic.
> + if (BId == Builtin::BIbzero ||
> + (CallLoc.isMacroID() && Lexer::getImmediateMacroName(
> + CallLoc, SM, S.getLangOpts()) ==
> "bzero")) {
> + S.Diag(DiagLoc, diag::warn_suspicious_bzero_size);
> + S.Diag(DiagLoc, diag::note_suspicious_bzero_size_silence);
> + } else {
> + S.Diag(DiagLoc, diag::warn_suspicious_sizeof_memset) << 0;
> + S.Diag(DiagLoc, diag::note_suspicious_sizeof_memset_silence) << 0;
> + }
> + return;
> + }
> +
> + // If the second argument to a memset is a sizeof expression and the
> third
> + // isn't, this is also likely an error. This should catch
> + // 'memset(buf, sizeof(buf), 0xff)'.
> + if (BId == Builtin::BImemset &&
> + doesExprLikelyComputeSize(Call->getArg(1)) &&
> + !doesExprLikelyComputeSize(Call->getArg(2))) {
> + SourceLocation DiagLoc = Call->getArg(1)->getExprLoc();
> + S.Diag(DiagLoc, diag::warn_suspicious_sizeof_memset) << 1;
> + S.Diag(DiagLoc, diag::note_suspicious_sizeof_memset_silence) << 1;
> + return;
> + }
> +}
> +
> /// Check for dangerous or invalid arguments to memset().
> ///
> /// This issues warnings on known problematic, dangerous or unspecified
> @@ -8771,6 +8853,9 @@ void Sema::CheckMemaccessArguments(const
> Call->getLocStart(),
> Call->getRParenLoc()))
> return;
>
> + // Catch cases like 'memset(buf, sizeof(buf), 0)'.
> + CheckMemaccessSize(*this, BId, Call);
> +
> // We have special checking when the length is a sizeof expression.
> QualType SizeOfArgTy = getSizeOfArgType(LenExpr);
> const Expr *SizeOfArg = getSizeOfExprArg(LenExpr);
>
> Added: cfe/trunk/test/Sema/transpose-memset.c
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/transpose-memset.c?rev=337470&view=auto
>
> ==============================================================================
> --- cfe/trunk/test/Sema/transpose-memset.c (added)
> +++ cfe/trunk/test/Sema/transpose-memset.c Thu Jul 19 09:46:15 2018
> @@ -0,0 +1,60 @@
> +// RUN: %clang_cc1 -Wmemset-transposed-args -verify %s
> +// RUN: %clang_cc1 -xc++ -Wmemset-transposed-args -verify %s
> +
> +#define memset(...) __builtin_memset(__VA_ARGS__)
> +#define bzero(x,y) __builtin_memset(x, 0, y)
> +#define real_bzero(x,y) __builtin_bzero(x,y)
> +
> +int array[10];
> +int *ptr;
> +
> +int main() {
> + memset(array, sizeof(array), 0); // expected-warning{{'size' argument
> to memset is '0'; did you mean to transpose the last two arguments?}}
> expected-note{{parenthesize the third argument to silence}}
> + memset(array, sizeof(array), 0xff); // expected-warning{{setting buffer
> to a 'sizeof' expression; did you mean to transpose the last two
> arguments?}} expected-note{{cast the second argument to 'int' to silence}}
> + memset(ptr, sizeof(ptr), 0); // expected-warning{{'size' argument to
> memset is '0'; did you mean to transpose the last two arguments?}}
> expected-note{{parenthesize the third argument to silence}}
> + memset(ptr, sizeof(*ptr) * 10, 1); // expected-warning{{setting buffer
> to a 'sizeof' expression; did you mean to transpose the last two
> arguments?}} expected-note{{cast the second argument to 'int' to silence}}
> + memset(ptr, 10 * sizeof(int *), 1); // expected-warning{{setting buffer
> to a 'sizeof' expression; did you mean to transpose the last two
> arguments?}} expected-note{{cast the second argument to 'int' to silence}}
> + memset(ptr, 10 * sizeof(int *) + 10, 0xff); //
> expected-warning{{setting buffer to a 'sizeof' expression; did you mean to
> transpose the last two arguments?}} expected-note{{cast the second argument
> to 'int' to silence}}
> + memset(ptr, sizeof(char) * sizeof(int *), 0xff); //
> expected-warning{{setting buffer to a 'sizeof' expression; did you mean to
> transpose the last two arguments?}} expected-note{{cast the second argument
> to 'int' to silence}}
> + memset(array, sizeof(array), sizeof(array)); // Uh... fine I guess.
> + memset(array, 0, sizeof(array));
> + memset(ptr, 0, sizeof(int *) * 10);
> + memset(array, (int)sizeof(array), (0)); // no warning
> + memset(array, (int)sizeof(array), 32); // no warning
> + memset(array, 32, (0)); // no warning
> +
> + bzero(ptr, 0); // expected-warning{{'size' argument to bzero is '0'}}
> expected-note{{parenthesize the second argument to silence}}
> + real_bzero(ptr, 0); // expected-warning{{'size' argument to bzero is
> '0'}} expected-note{{parenthesize the second argument to silence}}
> +}
> +
> +void macros() {
> +#define ZERO 0
> + int array[10];
> + memset(array, 0xff, ZERO); // no warning
> + // Still emit a diagnostic for memsetting a sizeof expression:
> + memset(array, sizeof(array), ZERO); // expected-warning{{'sizeof'}}
> expected-note{{cast}}
> + bzero(array, ZERO); // no warning
> + real_bzero(array, ZERO); // no warning
> +#define NESTED_DONT_DIAG \
> + memset(array, 0xff, ZERO); \
> + real_bzero(array, ZERO);
> +
> + NESTED_DONT_DIAG;
> +
> +#define NESTED_DO_DIAG \
> + memset(array, 0xff, 0); \
> + real_bzero(array, 0)
> +
> + NESTED_DO_DIAG; // expected-warning{{'size' argument to memset}}
> expected-warning{{'size' argument to bzero}} expected-note2{{parenthesize}}
> +
> +#define FN_MACRO(p) \
> + memset(array, 0xff, p)
> +
> + FN_MACRO(ZERO);
> + FN_MACRO(0); // FIXME: should we diagnose this?
> +
> + __builtin_memset(array, 0, ZERO); // no warning
> + __builtin_bzero(array, ZERO);
> + __builtin_memset(array, 0, 0); // expected-warning{{'size' argument to
> memset}} // expected-note{{parenthesize}}
> + __builtin_bzero(array, 0); // expected-warning{{'size' argument to
> bzero}} // expected-note{{parenthesize}}
> +}
>
>
> _______________________________________________
> cfe-commits mailing list
> cfe-commits at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20180721/60500796/attachment-0001.html>
More information about the cfe-commits
mailing list