1d3ef5f122
Add functions exposed via the MSAN interface to enable MSAN within binaries that perform manual stack switching (e.g. through using fibers or coroutines). This functionality is analogous to the fiber APIs available for ASAN and TSAN. Fixes google/sanitizers#1232 Reviewed By: vitalybuka Differential Revision: https://reviews.llvm.org/D86471
69 lines
2.1 KiB
C++
69 lines
2.1 KiB
C++
// RUN: %clangxx_msan -O0 %s -o %t && %run %t
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#include <assert.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <ucontext.h>
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#include <unistd.h>
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#include <sanitizer/msan_interface.h>
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namespace {
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const int kStackSize = 1 << 20;
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char fiber_stack[kStackSize] = {};
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ucontext_t main_ctx;
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ucontext_t fiber_ctx;
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void fiber() {
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printf("%s: entering fiber\n", __FUNCTION__);
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// This fiber was switched into from main. Verify the details of main's stack
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// have been populated by MSAN.
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const void *previous_stack_bottom = nullptr;
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size_t previous_stack_size = 0;
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__msan_finish_switch_fiber(&previous_stack_bottom, &previous_stack_size);
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assert(previous_stack_bottom != nullptr);
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assert(previous_stack_size != 0);
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printf("%s: implicitly swapcontext to main\n", __FUNCTION__);
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__msan_start_switch_fiber(previous_stack_bottom, previous_stack_size);
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}
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} // namespace
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// Set up a fiber, switch to it, and switch back, invoking __msan_*_switch_fiber
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// functions along the way. At each step, validate the correct stack addresses and
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// sizes are returned from those functions.
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int main(int argc, char **argv) {
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if (getcontext(&fiber_ctx) == -1) {
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perror("getcontext");
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_exit(1);
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}
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fiber_ctx.uc_stack.ss_sp = fiber_stack;
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fiber_ctx.uc_stack.ss_size = sizeof(fiber_stack);
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fiber_ctx.uc_link = &main_ctx;
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makecontext(&fiber_ctx, fiber, 0);
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// Tell MSAN a fiber switch is about to occur, then perform the switch
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printf("%s: swapcontext to fiber\n", __FUNCTION__);
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__msan_start_switch_fiber(fiber_stack, kStackSize);
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if (swapcontext(&main_ctx, &fiber_ctx) == -1) {
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perror("swapcontext");
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_exit(1);
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}
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// The fiber switched to above now switched back here. Tell MSAN that switch
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// is complete and verify the fiber details return by MSAN are correct.
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const void *previous_stack_bottom = nullptr;
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size_t previous_stack_size = 0;
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__msan_finish_switch_fiber(&previous_stack_bottom, &previous_stack_size);
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assert(previous_stack_bottom == fiber_stack);
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assert(previous_stack_size == kStackSize);
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printf("%s: exiting\n", __FUNCTION__);
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return 0;
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}
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