Julian Lettner c814a6a425 [Sanitizers] UBSan unreachable incompatible with ASan in the presence of noreturn calls ... Summary: UBSan wants to detect when unreachable code is actually reached, so it adds instrumentation before every `unreachable` instruction. However, the optimizer will remove code after calls to functions marked with `noreturn`. To avoid this UBSan removes `noreturn` from both the call instruction as well as from the function itself. Unfortunately, ASan relies on this annotation to unpoison the stack by inserting calls to `_asan_handle_no_return` before `noreturn` functions. This is important for functions that do not return but access the the stack memory, e.g., unwinder functions *like* `longjmp` (`longjmp` itself is actually "double-proofed" via its interceptor). The result is that when ASan and UBSan are combined, the `noreturn` attributes are missing and ASan cannot unpoison the stack, so it has false positives when stack unwinding is used. Changes: # UBSan now adds the `expect_noreturn` attribute whenever it removes the `noreturn` attribute from a function # ASan additionally checks for the presence of this attribute Generated code: ``` call void @__asan_handle_no_return // Additionally inserted to avoid false positives call void @longjmp call void @__asan_handle_no_return call void @__ubsan_handle_builtin_unreachable unreachable ``` The second call to `__asan_handle_no_return` is redundant. This will be cleaned up in a follow-up patch. rdar://problem/40723397 Reviewers: delcypher, eugenis Tags: #sanitizers Differential Revision: https://reviews.llvm.org/D56624 llvm-svn: 352003		2019-01-24 01:06:19 +00:00
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Reader	[Sanitizers] UBSan unreachable incompatible with ASan in the presence of noreturn calls	2019-01-24 01:06:19 +00:00
Writer	[Sanitizers] UBSan unreachable incompatible with ASan in the presence of noreturn calls	2019-01-24 01:06:19 +00:00
CMakeLists.txt
LLVMBuild.txt	Update the file headers across all of the LLVM projects in the monorepo	2019-01-19 08:50:56 +00:00