Bug Summary

File:root/firefox-clang/memory/replace/dmd/test/SmokeDMD.cpp
Warning:line 79, column 3
1st function call argument is an uninitialized value

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -O0 -analyze -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name SmokeDMD.cpp -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -fhalf-no-semantic-interposition -mframe-pointer=all -relaxed-aliasing -ffp-contract=off -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fdebug-compilation-dir=/root/firefox-clang/obj-x86_64-pc-linux-gnu/memory/replace/dmd/test -fcoverage-compilation-dir=/root/firefox-clang/obj-x86_64-pc-linux-gnu/memory/replace/dmd/test -resource-dir /usr/lib/llvm-23/lib/clang/23 -include /root/firefox-clang/config/gcc_hidden.h -include /root/firefox-clang/obj-x86_64-pc-linux-gnu/mozilla-config.h -D _GLIBCXX_ASSERTIONS=1 -I /root/firefox-clang/obj-x86_64-pc-linux-gnu/dist/system_wrappers -U _FORTIFY_SOURCE -D _FORTIFY_SOURCE=2 -D DEBUG=1 -D MOZ_HAS_MOZGLUE -D MOZ_NO_MOZALLOC -I /root/firefox-clang/memory/replace/dmd/test -I /root/firefox-clang/obj-x86_64-pc-linux-gnu/memory/replace/dmd/test -I /root/firefox-clang/obj-x86_64-pc-linux-gnu/dist/include -I /root/firefox-clang/obj-x86_64-pc-linux-gnu/dist/include/nspr -I /root/firefox-clang/obj-x86_64-pc-linux-gnu/dist/include/nss -D MOZILLA_CLIENT -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/16/../../../../include/c++/16 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/16/../../../../include/x86_64-linux-gnu/c++/16 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/16/../../../../include/c++/16/backward -internal-isystem /usr/lib/llvm-23/lib/clang/23/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/16/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -Wno-error=pessimizing-move -Wno-error=large-by-value-copy=128 -Wno-error=implicit-int-float-conversion -Wno-error=thread-safety-analysis -Wno-error=tautological-type-limit-compare -Wno-invalid-offsetof -Wno-range-loop-analysis -Wno-deprecated-anon-enum-enum-conversion -Wno-deprecated-enum-enum-conversion -Wno-inline-new-delete -Wno-error=deprecated-declarations -Wno-error=array-bounds -Wno-error=free-nonheap-object -Wno-error=atomic-alignment -Wno-error=deprecated-builtins -Wno-psabi -Wno-error=builtin-macro-redefined -Wno-vla-cxx-extension -Wno-unknown-warning-option -Wno-character-conversion -std=gnu++20 -fdeprecated-macro -ferror-limit 19 -fstrict-flex-arrays=1 -stack-protector 2 -fstack-clash-protection -ftrivial-auto-var-init=pattern -fno-rtti -fgnuc-version=4.2.1 -fno-implicit-modules -fskip-odr-check-in-gmf -fno-sized-deallocation -fno-aligned-allocation -fdiagnostics-absolute-paths -analyzer-checker optin.performance.Padding -analyzer-output=html -analyzer-config stable-report-filename=true -mllvm -dwarf-linkage-names=Abstract -faddrsig -fdwarf2-cfi-asm -o /tmp/scan-build-2026-09-01-224014-2642839-1 -x c++ /root/firefox-clang/memory/replace/dmd/test/SmokeDMD.cpp
1/* This Source Code Form is subject to the terms of the Mozilla Public
2 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
3 * You can obtain one at http://mozilla.org/MPL/2.0/. */
4
5// This program is used by the DMD xpcshell test. It is run under DMD and
6// produces some output. The xpcshell test then post-processes and checks this
7// output.
8//
9// Note that this file does not have "Test" or "test" in its name, because that
10// will cause the build system to not record breakpad symbols for it, which
11// will stop the post-processing (which includes stack fixing) from working
12// correctly.
13
14// This is required on some systems such as Fedora to allow
15// building with -O0 together with --warnings-as-errors due to
16// a check in /usr/include/features.h
17#undef _FORTIFY_SOURCE
18
19#include <errno(*__errno_location ()).h>
20#include <stdio.h>
21#include <stdlib.h>
22
23#include "mozilla/Assertions.h"
24#include "mozilla/JSONWriter.h"
25#include "mozilla/Sprintf.h"
26#include "mozilla/UniquePtr.h"
27#include "DMD.h"
28
29using mozilla::MakeUnique;
30using namespace mozilla::dmd;
31
32MOZ_RUNINIT DMDFuncs::Singleton DMDFuncs::sSingleton;
33
34class FpWriteFunc final : public mozilla::JSONWriteFunc {
35 public:
36 explicit FpWriteFunc(const char* aFilename) {
37 mFp = fopen(aFilename, "w");
38 if (!mFp) {
39 fprintf(stderrstderr, "SmokeDMD: can't create %s file: %s\n", aFilename,
40 strerror(errno(*__errno_location ())));
41 exit(1);
42 }
43 }
44
45 ~FpWriteFunc() { fclose(mFp); }
46
47 void Write(const mozilla::Span<const char>& aStr) final {
48 for (const char c : aStr) {
49 fputc(c, mFp);
50 }
51 }
52
53 private:
54 FILE* mFp;
55};
56
57// This stops otherwise-unused variables from being optimized away.
58static void UseItOrLoseIt(void* aPtr, int aSeven) {
59 char buf[64];
60 int n = SprintfLiteral(buf, "%p\n", aPtr);
61 if (n == 20 + aSeven) {
62 fprintf(stderrstderr, "well, that is surprising");
63 }
64}
65
66// This function checks that heap blocks that have the same stack trace but
67// different (or no) reporters get aggregated separately.
68void Foo(int aSeven) {
69 char* a[6];
70 for (int i = 0; i < aSeven - 1; i++) {
1
Assuming the condition is false
→
2
←
Loop condition is false. Execution continues on line 79
→
71 a[i] = (char*)malloc(128 - 16 * i);
72 UseItOrLoseIt(a[i], aSeven);
73 }
74
75 // Oddly, some versions of clang will cause identical stack traces to be
76 // generated for adjacent calls to Report(), which breaks the test. Inserting
77 // the UseItOrLoseIt() calls in between is enough to prevent this.
78
79 Report(a[2]); // reported
3
←
1st function call argument is an uninitialized value
80
81 UseItOrLoseIt(a[2], aSeven);
82
83 for (int i = 0; i < aSeven - 5; i++) {
84 Report(a[i]); // reported
85 UseItOrLoseIt(a[i], aSeven);
86 }
87
88 UseItOrLoseIt(a[2], aSeven);
89
90 Report(a[3]); // reported
91
92 // a[4], a[5] unreported
93}
94
95void TestEmpty(const char* aTestName, const char* aMode) {
96 char filename[128];
97 SprintfLiteral(filename, "complete-%s-%s.json", aTestName, aMode);
98 auto f = MakeUnique<FpWriteFunc>(filename);
99
100 char options[128];
101 SprintfLiteral(options, "--mode=%s --stacks=full", aMode);
102 ResetEverything(options);
103
104 // Zero for everything.
105 Analyze(std::move(f));
106}
107
108void TestFull(const char* aTestName, int aNum, const char* aMode, int aSeven) {
109 char filename[128];
110 SprintfLiteral(filename, "complete-%s%d-%s.json", aTestName, aNum, aMode);
111 auto f = MakeUnique<FpWriteFunc>(filename);
112
113 // The --show-dump-stats=yes is there just to give that option some basic
114 // testing, e.g. ensure it doesn't crash. It's hard to test much beyond that.
115 char options[128];
116 SprintfLiteral(options, "--mode=%s --stacks=full --show-dump-stats=yes",
117 aMode);
118 ResetEverything(options);
119
120 // Analyze 1: 1 freed, 9 out of 10 unreported.
121 // Analyze 2: still present and unreported.
122 int i;
123 char* a = nullptr;
124 for (i = 0; i < aSeven + 3; i++) {
125 a = (char*)malloc(100);
126 UseItOrLoseIt(a, aSeven);
127 }
128 free(a);
129
130 // A no-op.
131 free(nullptr);
132
133 // Note: 16 bytes is the smallest requested size that gives consistent
134 // behaviour across all platforms with jemalloc.
135 // Analyze 1: reported.
136 // Analyze 2: thrice-reported.
137 char* a2 = (char*)malloc(16);
138 Report(a2);
139
140 // Analyze 1: reported.
141 // Analyze 2: reportedness carries over, due to ReportOnAlloc.
142 char* b = (char*)malloc(10);
143 ReportOnAlloc(b);
144
145 // ReportOnAlloc, then freed.
146 // Analyze 1: freed, irrelevant.
147 // Analyze 2: freed, irrelevant.
148 char* b2 = (char*)malloc(16);
149 ReportOnAlloc(b2);
150 free(b2);
151
152 // Analyze 1: reported 4 times.
153 // Analyze 2: freed, irrelevant.
154 char* c = (char*)calloc(10, 3);
155 Report(c);
156 for (int i = 0; i < aSeven - 4; i++) {
157 Report(c);
158 }
159
160 // Analyze 1: ignored.
161 // Analyze 2: irrelevant.
162 Report((void*)(intptr_t)i);
163
164 // jemalloc rounds this up to 8192.
165 // Analyze 1: reported.
166 // Analyze 2: freed.
167 char* e = (char*)malloc(4096);
168 e = (char*)realloc(e, 7169);
169 Report(e);
170
171 // First realloc is like malloc; second realloc is shrinking.
172 // Analyze 1: reported.
173 // Analyze 2: re-reported.
174 char* e2 = (char*)realloc(nullptr, 1024);
175 e2 = (char*)realloc(e2, 512);
176 Report(e2);
177
178 // First realloc is like malloc; second realloc creates a min-sized block.
179 // XXX: on Windows, second realloc frees the block.
180 // Analyze 1: reported.
181 // Analyze 2: freed, irrelevant.
182 char* e3 = (char*)realloc(nullptr, 1023);
183 // e3 = (char*) realloc(e3, 0);
184 MOZ_ASSERT(e3)do { static_assert( mozilla::detail::AssertionConditionType<
decltype(e3)>::isValid, "invalid assertion condition"); if
((__builtin_expect(!!(!(!!(e3))), 0))) { do { } while (false
); MOZ_ReportAssertionFailure("e3", "/root/firefox-clang/memory/replace/dmd/test/SmokeDMD.cpp"
, 184); AnnotateMozCrashReason("MOZ_ASSERT" "(" "e3" ")"); do
{ MOZ_CrashSequence(__null, 184); __attribute__((nomerge)) ::
abort(); } while (false); } } while (false);
185 Report(e3);
186
187 // Analyze 1: freed, irrelevant.
188 // Analyze 2: freed, irrelevant.
189 char* f1 = (char*)malloc(64);
190 UseItOrLoseIt(f1, aSeven);
191 free(f1);
192
193 // Analyze 1: ignored.
194 // Analyze 2: irrelevant.
195 Report((void*)(intptr_t)0x0);
196
197 // Analyze 1: mixture of reported and unreported.
198 // Analyze 2: all unreported.
199 Foo(aSeven);
200
201 // Analyze 1: twice-reported.
202 // Analyze 2: twice-reported.
203 char* g1 = (char*)malloc(77);
204 ReportOnAlloc(g1);
205 ReportOnAlloc(g1);
206
207 // Analyze 1: mixture of reported and unreported.
208 // Analyze 2: all unreported.
209 // Nb: this Foo() call is deliberately not adjacent to the previous one. See
210 // the comment about adjacent calls in Foo() for more details.
211 Foo(aSeven);
212
213 // Analyze 1: twice-reported.
214 // Analyze 2: once-reported.
215 char* g2 = (char*)malloc(78);
216 Report(g2);
217 ReportOnAlloc(g2);
218
219 // Analyze 1: twice-reported.
220 // Analyze 2: once-reported.
221 char* g3 = (char*)malloc(79);
222 ReportOnAlloc(g3);
223 Report(g3);
224
225 // All the odd-ball ones.
226 // Analyze 1: all unreported.
227 // Analyze 2: all freed, irrelevant.
228 // XXX: no memalign on Mac
229 // void* w = memalign(64, 65); // rounds up to 128
230 // UseItOrLoseIt(w, aSeven);
231
232 // XXX: posix_memalign doesn't work on B2G
233 // void* x;
234 // posix_memalign(&y, 128, 129); // rounds up to 256
235 // UseItOrLoseIt(x, aSeven);
236
237 // XXX: valloc doesn't work on Windows.
238 // void* y = valloc(1); // rounds up to 4096
239 // UseItOrLoseIt(y, aSeven);
240
241 // XXX: C11 only
242 // void* z = aligned_alloc(64, 256);
243 // UseItOrLoseIt(z, aSeven);
244
245 if (aNum == 1) {
246 // Analyze 1.
247 Analyze(std::move(f));
248 }
249
250 ClearReports();
251
252 //---------
253
254 Report(a2);
255 Report(a2);
256 free(c);
257 free(e);
258 Report(e2);
259 free(e3);
260 // free(w);
261 // free(x);
262 // free(y);
263 // free(z);
264
265 // Do some allocations that will only show up in cumulative mode.
266 for (int i = 0; i < 100; i++) {
267 void* v = malloc(128);
268 UseItOrLoseIt(v, aSeven);
269 free(v);
270 }
271
272 if (aNum == 2) {
273 // Analyze 2.
274 Analyze(std::move(f));
275 }
276}
277
278void TestPartial(const char* aTestName, const char* aMode, int aSeven) {
279 char filename[128];
280 SprintfLiteral(filename, "complete-%s-%s.json", aTestName, aMode);
281 auto f = MakeUnique<FpWriteFunc>(filename);
282
283 char options[128];
284 SprintfLiteral(options, "--mode=%s", aMode);
285 ResetEverything(options);
286
287 int kTenThousand = aSeven + 9993;
288 char* s;
289
290 // The output of this function is deterministic but it relies on the
291 // probability and seeds given to the FastBernoulliTrial instance in
292 // ResetBernoulli(). If they change, the output will change too.
293
294 // Expected fraction with stacks: (1 - (1 - 0.003) ** 16) = 0.0469.
295 // So we expect about 0.0469 * 10000 == 469.
296 // We actually get 511.
297 for (int i = 0; i < kTenThousand; i++) {
298 s = (char*)malloc(16);
299 UseItOrLoseIt(s, aSeven);
300 }
301
302 // Expected fraction with stacks: (1 - (1 - 0.003) ** 128) = 0.3193.
303 // So we expect about 0.3193 * 10000 == 3193.
304 // We actually get 3136.
305 for (int i = 0; i < kTenThousand; i++) {
306 s = (char*)malloc(128);
307 UseItOrLoseIt(s, aSeven);
308 }
309
310 // Expected fraction with stacks: (1 - (1 - 0.003) ** 1024) = 0.9539.
311 // So we expect about 0.9539 * 10000 == 9539.
312 // We actually get 9531.
313 for (int i = 0; i < kTenThousand; i++) {
314 s = (char*)malloc(1024);
315 UseItOrLoseIt(s, aSeven);
316 }
317
318 Analyze(std::move(f));
319}
320
321void TestScan(int aSeven) {
322 auto f = MakeUnique<FpWriteFunc>("basic-scan.json");
323
324 ResetEverything("--mode=scan");
325
326 uintptr_t* p = (uintptr_t*)malloc(6 * sizeof(uintptr_t));
327 UseItOrLoseIt(p, aSeven);
328
329 // Hard-coded values checked by scan-test.py
330 p[0] = 0x123; // outside a block, small value
331 p[1] = 0x0; // null
332 p[2] = (uintptr_t)((uint8_t*)p - 1); // pointer outside a block, but nearby
333 p[3] = (uintptr_t)p; // pointer to start of a block
334 p[4] = (uintptr_t)((uint8_t*)p + 1); // pointer into a block
335 p[5] = 0x0; // trailing null
336
337 Analyze(std::move(f));
338}
339
340void RunTests() {
341 // This test relies on the compiler not doing various optimizations, such as
342 // eliding unused malloc() calls or unrolling loops with fixed iteration
343 // counts. So we compile it with -O0 (or equivalent), which probably prevents
344 // that. We also use the following variable for various loop iteration
345 // counts, just in case compilers might unroll very small loops even with
346 // -O0.
347 int seven = 7;
348
349 // Make sure that DMD is actually running; it is initialized on the first
350 // allocation.
351 int* x = (int*)malloc(100);
352 UseItOrLoseIt(x, seven);
353 MOZ_RELEASE_ASSERT(IsRunning())do { static_assert( mozilla::detail::AssertionConditionType<
decltype(IsRunning())>::isValid, "invalid assertion condition"
); if ((__builtin_expect(!!(!(!!(IsRunning()))), 0))) { do { }
while (false); MOZ_ReportAssertionFailure("IsRunning()", "/root/firefox-clang/memory/replace/dmd/test/SmokeDMD.cpp"
, 353); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "IsRunning()"
")"); do { MOZ_CrashSequence(__null, 353); __attribute__((nomerge
)) ::abort(); } while (false); } } while (false);
354
355 // Please keep this in sync with run_test in test_dmd.js.
356
357 TestEmpty("empty", "live");
358 TestEmpty("empty", "dark-matter");
359 TestEmpty("empty", "cumulative");
360
361 TestFull("full", 1, "live", seven);
362 TestFull("full", 1, "dark-matter", seven);
363
364 TestFull("full", 2, "dark-matter", seven);
365 TestFull("full", 2, "cumulative", seven);
366
367 TestPartial("partial", "live", seven);
368
369 TestScan(seven);
370}
371
372int main() {
373 RunTests();
374
375 return 0;
376}