From 49285f43e5ed17206235e43c9cd17762d77ed275 Mon Sep 17 00:00:00 2001 From: Balazs Benics Date: Thu, 28 Oct 2021 11:03:02 +0200 Subject: [PATCH] [analyzer] sprintf is a taint propagator not a source Due to a typo, `sprintf()` was recognized as a taint source instead of a taint propagator. It was because an empty taint source list - which is the first parameter of the `TaintPropagationRule` - encoded the unconditional taint sources. This typo effectively turned the `sprintf()` into an unconditional taint source. This patch fixes that typo and demonstrated the correct behavior with tests. Reviewed By: martong Differential Revision: https://reviews.llvm.org/D112558 --- clang/lib/StaticAnalyzer/Checkers/GenericTaintChecker.cpp | 2 +- clang/test/Analysis/taint-generic.c | 10 ++++++++++ 2 files changed, 11 insertions(+), 1 deletion(-) diff --git a/clang/lib/StaticAnalyzer/Checkers/GenericTaintChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/GenericTaintChecker.cpp index 69e9cbd..66ef781 100644 --- a/clang/lib/StaticAnalyzer/Checkers/GenericTaintChecker.cpp +++ b/clang/lib/StaticAnalyzer/Checkers/GenericTaintChecker.cpp @@ -514,7 +514,7 @@ GenericTaintChecker::TaintPropagationRule::getTaintPropagationRule( if (OneOf("snprintf")) return {{1}, {0, ReturnValueIndex}, VariadicType::Src, 3}; if (OneOf("sprintf")) - return {{}, {0, ReturnValueIndex}, VariadicType::Src, 2}; + return {{1}, {0, ReturnValueIndex}, VariadicType::Src, 2}; if (OneOf("strcpy", "stpcpy", "strcat")) return {{1}, {0, ReturnValueIndex}}; if (OneOf("bcopy")) diff --git a/clang/test/Analysis/taint-generic.c b/clang/test/Analysis/taint-generic.c index 2cbd5801..90ab454 100644 --- a/clang/test/Analysis/taint-generic.c +++ b/clang/test/Analysis/taint-generic.c @@ -341,6 +341,16 @@ void constraintManagerShouldTreatAsOpaque(int rhs) { *(volatile int *) 0; // no-warning } +int sprintf_is_not_a_source(char *buf, char *msg) { + int x = sprintf(buf, "%s", msg); // no-warning + return 1 / x; // no-warning: 'sprintf' is not a taint source +} + +int sprintf_propagates_taint(char *buf, char *msg) { + scanf("%s", msg); + int x = sprintf(buf, "%s", msg); // propagate taint! + return 1 / x; // expected-warning {{Division by a tainted value, possibly zero}} +} // Test configuration int mySource1(); -- 2.7.4