diff --git a/clang/include/clang/StaticAnalyzer/Checkers/Checkers.td b/clang/include/clang/StaticAnalyzer/Checkers/Checkers.td --- a/clang/include/clang/StaticAnalyzer/Checkers/Checkers.td +++ b/clang/include/clang/StaticAnalyzer/Checkers/Checkers.td @@ -773,6 +773,11 @@ Dependencies<[SecuritySyntaxChecker]>, Documentation; +def decodeValueOfObjCType : Checker<"decodeValueOfObjCType">, + HelpText<"Warn on uses of the '-decodeValueOfObjCType:at:' method">, + Dependencies<[SecuritySyntaxChecker]>, + Documentation; + } // end "security.insecureAPI" let ParentPackage = Security in { diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp --- a/clang/lib/Driver/ToolChains/Clang.cpp +++ b/clang/lib/Driver/ToolChains/Clang.cpp @@ -2789,8 +2789,11 @@ CmdArgs.push_back("-analyzer-disable-checker=unix.Vfork"); } - if (Triple.isOSDarwin()) + if (Triple.isOSDarwin()) { CmdArgs.push_back("-analyzer-checker=osx"); + CmdArgs.push_back( + "-analyzer-checker=security.insecureAPI.decodeValueOfObjCType"); + } CmdArgs.push_back("-analyzer-checker=deadcode"); diff --git a/clang/lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp b/clang/lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp --- a/clang/lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp +++ b/clang/lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp @@ -49,6 +49,7 @@ DefaultBool check_vfork; DefaultBool check_FloatLoopCounter; DefaultBool check_UncheckedReturn; + DefaultBool check_decodeValueOfObjCType; CheckerNameRef checkName_bcmp; CheckerNameRef checkName_bcopy; @@ -63,6 +64,7 @@ CheckerNameRef checkName_vfork; CheckerNameRef checkName_FloatLoopCounter; CheckerNameRef checkName_UncheckedReturn; + CheckerNameRef checkName_decodeValueOfObjCType; }; class WalkAST : public StmtVisitor { @@ -83,6 +85,7 @@ // Statement visitor methods. void VisitCallExpr(CallExpr *CE); + void VisitObjCMessageExpr(ObjCMessageExpr *CE); void VisitForStmt(ForStmt *S); void VisitCompoundStmt (CompoundStmt *S); void VisitStmt(Stmt *S) { VisitChildren(S); } @@ -93,6 +96,7 @@ bool checkCall_strCommon(const CallExpr *CE, const FunctionDecl *FD); typedef void (WalkAST::*FnCheck)(const CallExpr *, const FunctionDecl *); + typedef void (WalkAST::*MsgCheck)(const ObjCMessageExpr *); // Checker-specific methods. void checkLoopConditionForFloat(const ForStmt *FS); @@ -110,6 +114,7 @@ void checkCall_rand(const CallExpr *CE, const FunctionDecl *FD); void checkCall_random(const CallExpr *CE, const FunctionDecl *FD); void checkCall_vfork(const CallExpr *CE, const FunctionDecl *FD); + void checkMsg_decodeValueOfObjCType(const ObjCMessageExpr *ME); void checkUncheckedReturnValue(CallExpr *CE); }; } // end anonymous namespace @@ -182,6 +187,20 @@ VisitChildren(CE); } +void WalkAST::VisitObjCMessageExpr(ObjCMessageExpr *ME) { + MsgCheck evalFunction = + llvm::StringSwitch(ME->getSelector().getAsString()) + .Case("decodeValueOfObjCType:at:", + &WalkAST::checkMsg_decodeValueOfObjCType) + .Default(nullptr); + + if (evalFunction) + (this->*evalFunction)(ME); + + // Recurse and check children. + VisitChildren(ME); +} + void WalkAST::VisitCompoundStmt(CompoundStmt *S) { for (Stmt *Child : S->children()) if (Child) { @@ -924,6 +943,54 @@ } //===----------------------------------------------------------------------===// +// Check: '-decodeValueOfObjCType:at:' should not be used. +// It is deprecated in favor of '-decodeValueOfObjCType:at:size:' due to +// likelihood of buffer overflows. +//===----------------------------------------------------------------------===// + +void WalkAST::checkMsg_decodeValueOfObjCType(const ObjCMessageExpr *ME) { + if (!filter.check_decodeValueOfObjCType) + return; + + // Check availability of the secure alternative: + // iOS 11+, macOS 10.13+, tvOS 11+, and watchOS 4.0+ + // FIXME: We probably shouldn't register the check if it's not available. + const TargetInfo &TI = AC->getASTContext().getTargetInfo(); + const llvm::Triple &T = TI.getTriple(); + const VersionTuple &VT = TI.getPlatformMinVersion(); + switch (T.getOS()) { + case llvm::Triple::IOS: + if (VT < VersionTuple(11, 0)) + return; + break; + case llvm::Triple::MacOSX: + if (VT < VersionTuple(10, 13)) + return; + break; + case llvm::Triple::WatchOS: + if (VT < VersionTuple(4, 0)) + return; + break; + case llvm::Triple::TvOS: + if (VT < VersionTuple(11, 0)) + return; + break; + default: + return; + } + + PathDiagnosticLocation MELoc = + PathDiagnosticLocation::createBegin(ME, BR.getSourceManager(), AC); + BR.EmitBasicReport( + AC->getDecl(), filter.checkName_decodeValueOfObjCType, + "Potential buffer overflow in '-decodeValueOfObjCType:at:'", "Security", + "Deprecated method '-decodeValueOfObjCType:at:' is insecure " + "as it can lead to potential buffer overflows. Use the safer " + "'-decodeValueOfObjCType:at:size:' method.", + MELoc, ME->getSourceRange()); +} + +//===----------------------------------------------------------------------===// // Check: Should check whether privileges are dropped successfully. // Originally: //===----------------------------------------------------------------------===// @@ -1035,3 +1102,4 @@ REGISTER_CHECKER(FloatLoopCounter) REGISTER_CHECKER(UncheckedReturn) REGISTER_CHECKER(DeprecatedOrUnsafeBufferHandling) +REGISTER_CHECKER(decodeValueOfObjCType) diff --git a/clang/test/Analysis/security-syntax-checks-nscoder.m b/clang/test/Analysis/security-syntax-checks-nscoder.m new file mode 100644 --- /dev/null +++ b/clang/test/Analysis/security-syntax-checks-nscoder.m @@ -0,0 +1,36 @@ +// RUN: %clang_analyze_cc1 -triple thumbv7-apple-ios11.0 -verify=available \ +// RUN: -analyzer-checker=security.insecureAPI.decodeValueOfObjCType %s +// RUN: %clang_analyze_cc1 -triple thumbv7-apple-ios10.0 -verify=notavailable \ +// RUN: -analyzer-checker=security.insecureAPI.decodeValueOfObjCType %s +// RUN: %clang_analyze_cc1 -triple x86_64-apple-macos10.13 -verify=available \ +// RUN: -analyzer-checker=security.insecureAPI.decodeValueOfObjCType %s +// RUN: %clang_analyze_cc1 -triple x86_64-apple-macos10.12 -verify=notavailable \ +// RUN: -analyzer-checker=security.insecureAPI.decodeValueOfObjCType %s +// RUN: %clang_analyze_cc1 -triple thumbv7-apple-watchos4.0 -verify=available \ +// RUN: -analyzer-checker=security.insecureAPI.decodeValueOfObjCType %s +// RUN: %clang_analyze_cc1 -triple thumbv7-apple-watchos3.0 -verify=notavailable \ +// RUN: -analyzer-checker=security.insecureAPI.decodeValueOfObjCType %s +// RUN: %clang_analyze_cc1 -triple thumbv7-apple-tvos11.0 -verify=available \ +// RUN: -analyzer-checker=security.insecureAPI.decodeValueOfObjCType %s +// RUN: %clang_analyze_cc1 -triple thumbv7-apple-tvos10.0 -verify=notavailable \ +// RUN: -analyzer-checker=security.insecureAPI.decodeValueOfObjCType %s + +// notavailable-no-diagnostics + +typedef unsigned long NSUInteger; + +@interface NSCoder +- (void)decodeValueOfObjCType:(const char *)type + at:(void *)data; +- (void)decodeValueOfObjCType:(const char *)type + at:(void *)data + size:(NSUInteger)size; +@end + +void test(NSCoder *decoder) { + // This would be a vulnerability on 64-bit platforms + // but not on 32-bit platforms. + NSUInteger x; + [decoder decodeValueOfObjCType:"I" at:&x]; // available-warning{{Deprecated method '-decodeValueOfObjCType:at:' is insecure as it can lead to potential buffer overflows. Use the safer '-decodeValueOfObjCType:at:size:' method}} + [decoder decodeValueOfObjCType:"I" at:&x size:sizeof(x)]; // no-warning +} diff --git a/clang/www/analyzer/available_checks.html b/clang/www/analyzer/available_checks.html --- a/clang/www/analyzer/available_checks.html +++ b/clang/www/analyzer/available_checks.html @@ -1446,6 +1446,22 @@ } + + + +