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[StaticAnalyzer] Relax the pre-condition of 'setsockopt' (#130683)

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For the unix function
`int setsockopt(int, int, int, const void *, socklen_t);`, the last two
parameters represent a buffer and a size.

In case the size is zero, buffer can be null. Previously, the hard-coded
pre-condition requires the buffer to never be null, which can cause
false positives.

(rdar://146678142)
This commit is contained in:
Ziqing Luo 2025-03-11 10:23:03 -07:00 committed by GitHub
parent f10a8706a1
commit 6501647508
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GPG Key ID: B5690EEEBB952194
2 changed files with 14 additions and 2 deletions
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5
clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
View File

@ -1797,7 +1797,8 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
auto IsNull = [&](ArgNo ArgN) {
return std::make_shared<NotNullConstraint>(ArgN, false);
};
auto NotNullBuffer = [&](ArgNo ArgN, ArgNo SizeArg1N, ArgNo SizeArg2N) {
auto NotNullBuffer = [&](ArgNo ArgN, ArgNo SizeArg1N,
std::optional<ArgNo> SizeArg2N = std::nullopt) {
return std::make_shared<NotNullBufferConstraint>(ArgN, SizeArg1N,
SizeArg2N);
};
@ -3365,7 +3366,7 @@ void StdLibraryFunctionsChecker::initFunctionSummaries(
Summary(NoEvalCall)
.Case(ReturnsZero, ErrnoMustNotBeChecked, GenericSuccessMsg)
.Case(ReturnsMinusOne, ErrnoNEZeroIrrelevant, GenericFailureMsg)
.ArgConstraint(NotNull(ArgNo(3)))
.ArgConstraint(NotNullBuffer(ArgNo(3), ArgNo(4)))
.ArgConstraint(
BufferSize(/*Buffer=*/ArgNo(3), /*BufSize=*/ArgNo(4)))
.ArgConstraint(

11
clang/test/Analysis/std-c-library-functions-POSIX.c
View File

@ -237,3 +237,14 @@ void test_readlinkat_bufsize_zero(int fd, char *Buf, size_t Bufsize) {
else
clang_analyzer_eval(Bufsize == 0); // expected-warning{{UNKNOWN}}
}
void test_setsockopt_bufptr_null(int x) {
char buf[10] = {0};
setsockopt(1, 2, 3, 0, 0);
setsockopt(1, 2, 3, buf, 10);
if (x)
setsockopt(1, 2, 3, buf, 11); // expected-warning{{The 4th argument to 'setsockopt' is a buffer with size 10 but should be a buffer with size equal to or greater than the value of the 5th argument (which is 11)}}
else
setsockopt(1, 2, 3, 0, 10); // expected-warning{{The 4th argument to 'setsockopt' is NULL but should not be NULL}}
}