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Check for either `violate()` or `ViolateIndirect()` in stack trace 

Depending on architecture and optimization level, the compiler may choose to
not generate full stack frames, even with no-inline and no tail-call
attributes.

PiperOrigin-RevId: 372339987
Change-Id: I42043131bbb6092ff234e80ae9047f7a2bf31161
pull/87/head
Christian Blichmann 2021-05-06 07:35:41 -07:00 committed by Copybara-Service
parent 0750216bc1
commit 5c7903ecd9
2 changed files with 19 additions and 8 deletions
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17
sandboxed_api/examples/stringop/lib/stringop.cc
View File

@ -79,17 +79,20 @@ extern "C" const void* get_raw_c_string() { return "Ten chars."; }
extern "C" void nop() {}
// The "no tail-call" annotation and the additional indirection ensure that this
// function shows up in the violation stack trace. Otherwise, depending on
// optimization level and optimizer aggressiveness, functions may be inlined,
// hoisted or omitted (in case of tail calls).
// The "no tail-call" annotation and the additional indirection ensure that
// either this function or its calling function shows up in the violation stack
// trace. Otherwise, depending on optimization level and optimizer
// aggressiveness, functions may be inlined, hoisted or omitted (in case of tail
// calls).
static ABSL_ATTRIBUTE_NOINLINE ABSL_ATTRIBUTE_NO_TAIL_CALL void
ViolateIndirect() {
ptrace((__ptrace_request)990, 991, 992, 993);
ABSL_BLOCK_TAIL_CALL_OPTIMIZATION();
}
extern "C" void violate() {
// Using block syntax here, because SAPI's libclang based header generator won't
// parse the attribute annotations otherwise.
extern "C" {
ABSL_ATTRIBUTE_NOINLINE ABSL_ATTRIBUTE_NO_TAIL_CALL void violate() {
ViolateIndirect();
ABSL_BLOCK_TAIL_CALL_OPTIMIZATION();
}
}

10
sandboxed_api/sapi_test.cc
View File

@ -143,7 +143,15 @@ TEST(SapiTest, HasStackTraces) {
StringopApi api(sandbox.get());
EXPECT_THAT(api.violate(), StatusIs(absl::StatusCode::kUnavailable));
const auto& result = sandbox->AwaitResult();
EXPECT_THAT(result.GetStackTrace(), HasSubstr("ViolateIndirect"));
EXPECT_THAT(
result.GetStackTrace(),
// Check that at least one expected function is present in the stack
// trace.
// Note: Typically, in optimized builds, on x86-64, only
// "ViolateIndirect()" will be present in the stack trace. On POWER, all
// stack frames are generated, but libunwind will be unable to track
// "ViolateIndirect()" on the stack and instead show its IP as zero.
AnyOf(HasSubstr("ViolateIndirect"), HasSubstr("violate")));
EXPECT_THAT(result.final_status(), Eq(sandbox2::Result::VIOLATION));
}