Check for mprotect result
Failure to mark shadow stack page as writable will result in a SEGV
fault later when a function tries to save return addresses to shadow
stack. The engineer looking at the crash report would be very confused
because the program crashes at very beginning of an innocent looking
function. For ease of debugging, check for shadow stack errors early.
Test: th
Bug: 279808236
Bug: 253652966
Change-Id: Id2da68fa984b5dfb1846ed14aa7ededee7f2508f
diff --git a/libc/bionic/pthread_create.cpp b/libc/bionic/pthread_create.cpp
index b46c6cf..75226d3 100644
--- a/libc/bionic/pthread_create.cpp
+++ b/libc/bionic/pthread_create.cpp
@@ -137,7 +137,10 @@
// Make the stack read-write, and store its address in the register we're using as the shadow
// stack pointer. This is deliberately the only place where the address is stored.
char* scs = scs_aligned_guard_region + scs_offset;
- mprotect(scs, SCS_SIZE, PROT_READ | PROT_WRITE);
+ if (mprotect(scs, SCS_SIZE, PROT_READ | PROT_WRITE) == -1) {
+ async_safe_fatal("failed to mprotect() on shadow stack %p %d error %s", scs, SCS_SIZE,
+ strerror(errno));
+ }
#if defined(__aarch64__)
__asm__ __volatile__("mov x18, %0" ::"r"(scs));
#elif defined(__riscv)