1 // Check that ASan plays well with easy cases of makecontext/swapcontext.
2 
3 // RUN: %clangxx_asan -O0 %s -o %t && %run %t 2>&1 | FileCheck %s
4 // RUN: %clangxx_asan -O1 %s -o %t && %run %t 2>&1 | FileCheck %s
5 // RUN: %clangxx_asan -O2 %s -o %t && %run %t 2>&1 | FileCheck %s
6 // RUN: %clangxx_asan -O3 %s -o %t && %run %t 2>&1 | FileCheck %s
7 //
8 // This test is too sublte to try on non-x86 arch for now.
9 // Android and musl do not support swapcontext.
10 // REQUIRES: x86-target-arch && glibc-2.27
11 
12 #include <stdio.h>
13 #include <ucontext.h>
14 #include <unistd.h>
15 
16 ucontext_t orig_context;
17 ucontext_t child_context;
18 
19 const int kStackSize = 1 << 20;
20 
21 __attribute__((noinline))
22 void Throw() {
23   throw 1;
24 }
25 
26 __attribute__((noinline))
27 void ThrowAndCatch() {
28   try {
29     Throw();
30   } catch(int a) {
31     printf("ThrowAndCatch: %d\n", a);
32   }
33 }
34 
35 void Child(int mode) {
36   char x[32] = {0};  // Stack gets poisoned.
37   printf("Child: %p\n", x);
38   ThrowAndCatch();  // Simulate __asan_handle_no_return().
39   // (a) Do nothing, just return to parent function.
40   // (b) Jump into the original function. Stack remains poisoned unless we do
41   //     something.
42   if (mode == 1) {
43     if (swapcontext(&child_context, &orig_context) < 0) {
44       perror("swapcontext");
45       _exit(0);
46     }
47   }
48 }
49 
50 int Run(int arg, int mode, char *child_stack) {
51   printf("Child stack: %p\n", child_stack);
52   // Setup child context.
53   getcontext(&child_context);
54   child_context.uc_stack.ss_sp = child_stack;
55   child_context.uc_stack.ss_size = kStackSize / 2;
56   if (mode == 0) {
57     child_context.uc_link = &orig_context;
58   }
59   makecontext(&child_context, (void (*)())Child, 1, mode);
60   if (swapcontext(&orig_context, &child_context) < 0) {
61     perror("swapcontext");
62     return 0;
63   }
64   // Touch childs's stack to make sure it's unpoisoned.
65   for (int i = 0; i < kStackSize; i++) {
66     child_stack[i] = i;
67   }
68   return child_stack[arg];
69 }
70 
71 int main(int argc, char **argv) {
72   char stack[kStackSize + 1];
73   // CHECK: WARNING: ASan doesn't fully support makecontext/swapcontext
74   int ret = 0;
75   ret += Run(argc - 1, 0, stack);
76   printf("Test1 passed\n");
77   // CHECK: Test1 passed
78   ret += Run(argc - 1, 1, stack);
79   printf("Test2 passed\n");
80   // CHECK: Test2 passed
81   char *heap = new char[kStackSize + 1];
82   ret += Run(argc - 1, 0, heap);
83   printf("Test3 passed\n");
84   // CHECK: Test3 passed
85   ret += Run(argc - 1, 1, heap);
86   printf("Test4 passed\n");
87   // CHECK: Test4 passed
88 
89   delete [] heap;
90   return ret;
91 }
92