From a5fd234bf568100b8025bc29923beb2d9bb57d2f Mon Sep 17 00:00:00 2001 From: Giedrius Bacevicius Date: Tue, 7 Mar 2023 23:14:45 -0800 Subject: [PATCH] Zero size array causes crash in AsyncUDPSocket on llvm15 Summary: AsyncUDPSocket test cases are crashing when running under llvm15. During debugging it seems that the issue is the fact that the code tries to allocated 0 size array. Changing the code to prevent such allocation. This is not very clean why to fix, but I am not sure if there is better one. Please let me know if you have any suggestions. Sample crash: ``` $ buck test //folly/io/async/test:async_udp_socket_test ... stdout: Note: Google Test filter = AsyncUDPSocketTest.TestDetachAttach [==========] Running 1 test from 1 test suite. [----------] Global test environment set-up. [----------] 1 test from AsyncUDPSocketTest [ RUN ] AsyncUDPSocketTest.TestDetachAttach stderr: fbcode/folly/io/async/AsyncUDPSocket.cpp:699:10: runtime error: variable length array bound evaluates to non-positive value 0 #0 0x7f4d8ed93704 in folly::AsyncUDPSocket::writev(folly::SocketAddress const&, iovec const*, unsigned long, int) fbcode/folly/io/async/AsyncUDPSocket.cpp:698 #1 0x7f4d8ed9081f in folly::AsyncUDPSocket::writeGSO(folly::SocketAddress const&, std::unique_ptr> const&, int) fbcode/folly/io/async/AsyncUDPSocket.cpp:528 #2 0x7f4d8ed900b2 in folly::AsyncUDPSocket::write(folly::SocketAddress const&, std::unique_ptr> const&) fbcode/folly/io/async/AsyncUDPSocket.cpp:660 #3 0x350a05 in AsyncUDPSocketTest_TestDetachAttach_Test::TestBody() fbcode/folly/io/async/test/AsyncUDPSocketTest.cpp:914 #4 0x7f4d90dd1ad5 in testing::Test::Run() /home/engshare/third-party2/googletest/1.11.0/src/googletest/googletest/src/gtest.cc:2682:50 #5 0x7f4d90dd1ad5 in testing::Test::Run() /home/engshare/third-party2/googletest/1.11.0/src/googletest/googletest/src/gtest.cc:2672:6 #6 0x7f4d90dd1c64 in testing::TestInfo::Run() /home/engshare/third-party2/googletest/1.11.0/src/googletest/googletest/src/gtest.cc:2861:14 #7 0x7f4d90dd1c64 in testing::TestInfo::Run() /home/engshare/third-party2/googletest/1.11.0/src/googletest/googletest/src/gtest.cc:2833:6 #8 0x7f4d90dd2321 in testing::TestSuite::Run() /home/engshare/third-party2/googletest/1.11.0/src/googletest/googletest/src/gtest.cc:3015:31 #9 0x7f4d90dd2321 in testing::TestSuite::Run() /home/engshare/third-party2/googletest/1.11.0/src/googletest/googletest/src/gtest.cc:2993:6 #10 0x7f4d90dd2b1e in testing::internal::UnitTestImpl::RunAllTests() /home/engshare/third-party2/googletest/1.11.0/src/googletest/googletest/src/gtest.cc:5855:47 #11 0x7f4d90dd1d87 in bool testing::internal::HandleExceptionsInMethodIfSupported(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), char const*) /home/engshare/third-party2/googletest/1.11.0/src/googletest/googletest/src/gtest.cc:2665:29 #12 0x7f4d90dd1d87 in testing::UnitTest::Run() /home/engshare/third-party2/googletest/1.11.0/src/googletest/googletest/src/gtest.cc:5438:55 #13 0x7f4d90d5c990 in RUN_ALL_TESTS() fbcode/third-party-buck/platform010/build/googletest/include/gtest/gtest.h:2490 #14 0x7f4d90d5c618 in main fbcode/common/gtest/LightMain.cpp:20 #15 0x7f4d8ea2c656 in __libc_start_call_main /home/engshare/third-party2/glibc/2.34/src/glibc-2.34/csu/../sysdeps/nptl/libc_start_call_main.h:58:16 #16 0x7f4d8ea2c717 in __libc_start_main@GLIBC_2.2.5 /home/engshare/third-party2/glibc/2.34/src/glibc-2.34/csu/../csu/libc-start.c:409:3 #17 0x33ea60 in _start /home/engshare/third-party2/glibc/2.34/src/glibc-2.34/csu/../sysdeps/x86_64/start.S:116 ... ``` Reviewed By: russoue, dmm-fb Differential Revision: D43858875 fbshipit-source-id: 93749bab17027b6dfc0dbc01b6c183e501a5494c --- folly/io/async/AsyncUDPSocket.cpp | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/folly/io/async/AsyncUDPSocket.cpp b/folly/io/async/AsyncUDPSocket.cpp index 4445faa2dba..9d1bc0f4f55 100644 --- a/folly/io/async/AsyncUDPSocket.cpp +++ b/folly/io/async/AsyncUDPSocket.cpp @@ -693,6 +693,11 @@ ssize_t AsyncUDPSocket::writev( cmsgs_->size() * (CMSG_SPACE(sizeof(int)) / CMSG_SPACE(sizeof(uint16_t))); if (nontrivialCmsgs_.empty() && controlBufSize <= kSmallSizeMax) { + // Avoid allocating 0 length array. Doing so leads to exceptions + if (controlBufSize == 0) { + return writevImpl(&msg, gso); + } + // suppress "warning: variable length array 'control' is used [-Wvla]" FOLLY_PUSH_WARNING FOLLY_GNU_DISABLE_WARNING("-Wvla")