36 lines · cpp
1// RUN: %clangxx_msan -fsanitize-memory-track-origins=2 -O1 %s -o %t && not %run %t 2>&1 | FileCheck %s2 3// musl does not define FP_XSTATE_MAGIC1.4// REQUIRES: x86_64-target-arch && glibc-2.275 6#include <pthread.h>7#include <signal.h>8#include <stdint.h>9#include <ucontext.h>10 11void handler(int sig, siginfo_t *info, void *uctx) {12 volatile int uninit;13 auto *mctx = &static_cast<ucontext_t *>(uctx)->uc_mcontext;14 auto *fpregs = mctx->fpregs;15 // The member names differ across header versions, but the actual layout16 // is always the same. So avoid using members, just use arithmetic.17 const uint32_t *after_xmm =18 reinterpret_cast<const uint32_t *>(fpregs + 1) - 24;19 if (after_xmm[12] == FP_XSTATE_MAGIC1)20 reinterpret_cast<_xstate *>(mctx->fpregs)->ymmh.ymmh_space[0] = uninit;21 else22 mctx->gregs[REG_RAX] = uninit;23}24 25int main(int argc, char **argv) {26 struct sigaction act = {};27 act.sa_sigaction = handler;28 act.sa_flags = SA_SIGINFO;29 sigfillset(&act.sa_mask);30 sigaction(SIGPROF, &act, 0);31 pthread_kill(pthread_self(), SIGPROF);32 return 0;33}34 35// CHECK: WARNING: MemorySanitizer:36