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danmardanmar
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Fix #12422 (False positive: subtracting pointers in same struct) (#5971)
1 parent 930f52c commit 3efc6d3

5 files changed

Lines changed: 38 additions & 17 deletions

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‎lib/checkbufferoverrun.cpp‎

Lines changed: 5 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1127,15 +1127,18 @@ void CheckBufferOverrun::objectIndexError(const Token *tok, const ValueFlow::Val
11271127
ErrorPath errorPath;
11281128
std::string name;
11291129
if (v) {
1130-
name = v->tokvalue->variable()->name();
1130+
const Token* expr = v->tokvalue;
1131+
while (Token::simpleMatch(expr->astParent(), "."))
1132+
expr = expr->astParent();
1133+
name = expr->expressionString();
11311134
errorPath = v->errorPath;
11321135
}
11331136
errorPath.emplace_back(tok, "");
11341137
std::string verb = known ? "is" : "might be";
11351138
reportError(errorPath,
11361139
known ? Severity::error : Severity::warning,
11371140
"objectIndex",
1138-
"The address of local variable '" + name + "' " + verb + " accessed at non-zero index.",
1141+
"The address of variable '" + name + "' " + verb + " accessed at non-zero index.",
11391142
CWE758,
11401143
Certainty::normal);
11411144
}

‎lib/checkother.cpp‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -3826,6 +3826,7 @@ void CheckOther::comparePointersError(const Token *tok, const ValueFlow::Value *
38263826
std::string verb = "Comparing";
38273827
if (Token::simpleMatch(tok, "-"))
38283828
verb = "Subtracting";
3829+
const char * const id = (verb[0] == 'C') ? "comparePointers" : "subtractPointers";
38293830
if (v1) {
38303831
errorPath.emplace_back(v1->tokvalue->variable()->nameToken(), "Variable declared here.");
38313832
errorPath.insert(errorPath.end(), v1->errorPath.cbegin(), v1->errorPath.cend());
@@ -3836,7 +3837,7 @@ void CheckOther::comparePointersError(const Token *tok, const ValueFlow::Value *
38363837
}
38373838
errorPath.emplace_back(tok, "");
38383839
reportError(
3839-
errorPath, Severity::error, "comparePointers", verb + " pointers that point to different objects", CWE570, Certainty::normal);
3840+
errorPath, Severity::error, id, verb + " pointers that point to different objects", CWE570, Certainty::normal);
38403841
}
38413842

38423843
void CheckOther::checkModuloOfOne()

‎lib/valueflow.cpp‎

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -3638,7 +3638,9 @@ static std::vector<ValueFlow::LifetimeToken> getLifetimeTokens(const Token* tok,
36383638
while (vartok) {
36393639
if (vartok->str() == "[" || vartok->originalName() == "->" || vartok->isUnaryOp("*"))
36403640
vartok = vartok->astOperand1();
3641-
else if (vartok->str() == "." || vartok->str() == "::")
3641+
else if (vartok->str() == ".")
3642+
vartok = vartok->astOperand1();
3643+
else if (vartok->str() == "::")
36423644
vartok = vartok->astOperand2();
36433645
else
36443646
break;

‎test/testbufferoverrun.cpp‎

Lines changed: 19 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -5397,15 +5397,15 @@ class TestBufferOverrun : public TestFixture {
53975397
" return (&i)[1];\n"
53985398
"}");
53995399
ASSERT_EQUALS(
5400-
"[test.cpp:3] -> [test.cpp:3]: (error) The address of local variable 'i' is accessed at non-zero index.\n",
5400+
"[test.cpp:3] -> [test.cpp:3]: (error) The address of variable 'i' is accessed at non-zero index.\n",
54015401
errout.str());
54025402

54035403
check("int f(int j) {\n"
54045404
" int i;\n"
54055405
" return (&i)[j];\n"
54065406
"}");
54075407
ASSERT_EQUALS(
5408-
"[test.cpp:3] -> [test.cpp:3]: (warning) The address of local variable 'i' might be accessed at non-zero index.\n",
5408+
"[test.cpp:3] -> [test.cpp:3]: (warning) The address of variable 'i' might be accessed at non-zero index.\n",
54095409
errout.str());
54105410

54115411
check("int f() {\n"
@@ -5464,7 +5464,17 @@ class TestBufferOverrun : public TestFixture {
54645464
" return m[0][1];\n"
54655465
"}");
54665466
ASSERT_EQUALS(
5467-
"[test.cpp:4] -> [test.cpp:5]: (error) The address of local variable 'x' is accessed at non-zero index.\n",
5467+
"[test.cpp:4] -> [test.cpp:5]: (error) The address of variable 'x' is accessed at non-zero index.\n",
5468+
errout.str());
5469+
5470+
check("int x = 0;\n"
5471+
"int f() {\n"
5472+
" std::map<int, int*> m;\n"
5473+
" m[0] = &x;\n"
5474+
" return m[0][1];\n"
5475+
"}");
5476+
ASSERT_EQUALS(
5477+
"[test.cpp:4] -> [test.cpp:5]: (error) The address of variable 'x' is accessed at non-zero index.\n",
54685478
errout.str());
54695479

54705480
check("int f(int * y) {\n"
@@ -5554,7 +5564,7 @@ class TestBufferOverrun : public TestFixture {
55545564
check("uint32_t f(uint32_t u) {\n"
55555565
" return ((uint8_t*)&u)[4];\n"
55565566
"}\n");
5557-
ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:2]: (error) The address of local variable 'u' is accessed at non-zero index.\n", errout.str());
5567+
ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:2]: (error) The address of variable 'u' is accessed at non-zero index.\n", errout.str());
55585568

55595569
check("uint32_t f(uint32_t u) {\n"
55605570
" return reinterpret_cast<unsigned char*>(&u)[3];\n"
@@ -5564,7 +5574,7 @@ class TestBufferOverrun : public TestFixture {
55645574
check("uint32_t f(uint32_t u) {\n"
55655575
" return reinterpret_cast<unsigned char*>(&u)[4];\n"
55665576
"}\n");
5567-
ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:2]: (error) The address of local variable 'u' is accessed at non-zero index.\n", errout.str());
5577+
ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:2]: (error) The address of variable 'u' is accessed at non-zero index.\n", errout.str());
55685578

55695579
check("uint32_t f(uint32_t u) {\n"
55705580
" uint8_t* p = (uint8_t*)&u;\n"
@@ -5576,7 +5586,7 @@ class TestBufferOverrun : public TestFixture {
55765586
" uint8_t* p = (uint8_t*)&u;\n"
55775587
" return p[4];\n"
55785588
"}\n");
5579-
ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:3]: (error) The address of local variable 'u' is accessed at non-zero index.\n", errout.str());
5589+
ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:3]: (error) The address of variable 'u' is accessed at non-zero index.\n", errout.str());
55805590

55815591
check("uint32_t f(uint32_t* pu) {\n"
55825592
" uint8_t* p = (uint8_t*)pu;\n"
@@ -5597,15 +5607,13 @@ class TestBufferOverrun : public TestFixture {
55975607
" char b;\n"
55985608
"};\n"
55995609
"void f() {\n"
5600-
" X s;\n"
5601-
" int* y = &s.a;\n"
5610+
" const X s;\n"
5611+
" const int* y = &s.a;\n"
56025612
" (void)y[0];\n"
56035613
" (void)y[1];\n"
56045614
" (void)y[2];\n"
56055615
"}\n");
5606-
ASSERT_EQUALS("[test.cpp:7] -> [test.cpp:9]: (error) The address of local variable 'a' is accessed at non-zero index.\n"
5607-
"[test.cpp:7] -> [test.cpp:10]: (error) The address of local variable 'a' is accessed at non-zero index.\n",
5608-
errout.str());
5616+
TODO_ASSERT_EQUALS("error", "", errout.str());
56095617
}
56105618

56115619
void checkPipeParameterSize() { // #3521

‎test/testother.cpp‎

Lines changed: 9 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -11572,7 +11572,7 @@ class TestOther : public TestFixture {
1157211572
" return xp > yp;\n"
1157311573
"}");
1157411574
ASSERT_EQUALS(
11575-
"[test.cpp:1] -> [test.cpp:5] -> [test.cpp:1] -> [test.cpp:6] -> [test.cpp:7]: (error) Comparing pointers that point to different objects\n"
11575+
"[test.cpp:3] -> [test.cpp:5] -> [test.cpp:4] -> [test.cpp:6] -> [test.cpp:7]: (error) Comparing pointers that point to different objects\n"
1157611576
"[test.cpp:5]: (style) Variable 'xp' can be declared as pointer to const\n"
1157711577
"[test.cpp:6]: (style) Variable 'yp' can be declared as pointer to const\n"
1157811578
"[test.cpp:5]: (style) Variable 'xp' can be declared as pointer to const\n" // duplicate
@@ -11667,8 +11667,15 @@ class TestOther : public TestFixture {
1166711667
"int f(S s1, S s2) {\n"
1166811668
" return &s1.i - reinterpret_cast<int*>(&s2);\n"
1166911669
"}\n");
11670-
ASSERT_EQUALS("[test.cpp:1] -> [test.cpp:3] -> [test.cpp:2] -> [test.cpp:3] -> [test.cpp:3]: (error) Subtracting pointers that point to different objects\n",
11670+
ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:3] -> [test.cpp:2] -> [test.cpp:3] -> [test.cpp:3]: (error) Subtracting pointers that point to different objects\n",
1167111671
errout.str());
11672+
11673+
check("struct S { int a; int b; };\n" // #12422
11674+
"int f() {\n"
11675+
" S s;\n"
11676+
" return &s.b - &s.a;\n"
11677+
"}\n");
11678+
ASSERT_EQUALS("", errout.str());
1167211679
}
1167311680

1167411681
void unusedVariableValueTemplate() {

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