From 86602484a28fe345d9d164fe33d765d5e2791c58 Mon Sep 17 00:00:00 2001 From: Samuel Williams Date: Wed, 25 May 2022 18:13:04 +1200 Subject: Ensure we retain the main fiber stack bounds. --- cont.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) (limited to 'cont.c') diff --git a/cont.c b/cont.c index 12d79726ad..fba292ae9d 100644 --- a/cont.c +++ b/cont.c @@ -739,7 +739,8 @@ fiber_pool_stack_release(struct fiber_pool_stack * stack) fiber_pool_stack_free(&vacancy->stack); } #else - // This is entirely optional, but clears the dirty flag from the stack memory, so it won't get swapped to disk when there is memory pressure: + // This is entirely optional, but clears the dirty flag from the stack + // memory, so it won't get swapped to disk when there is memory pressure: if (stack->pool->free_stacks) { fiber_pool_stack_free(&vacancy->stack); } @@ -778,7 +779,16 @@ fiber_entry(struct coroutine_context * from, struct coroutine_context * to) rb_fiber_t *fiber = to->argument; #if defined(COROUTINE_SANITIZE_ADDRESS) - __sanitizer_finish_switch_fiber(to->fake_stack, NULL, NULL); + // Address sanitizer will copy the previous stack base and stack size into + // the "from" fiber. `coroutine_initialize_main` doesn't generally know the + // stack bounds (base + size). Therefore, the main fiber `stack_base` and + // `stack_size` will be NULL/0. It's specifically important in that case to + // get the (base+size) of the previous fiber and save it, so that later when + // we return to the main coroutine, we don't supply (NULL, 0) to + // __sanitizer_start_switch_fiber which royally messes up the internal state + // of ASAN and causes (sometimes) the following message: + // "WARNING: ASan is ignoring requested __asan_handle_no_return" + __sanitizer_finish_switch_fiber(to->fake_stack, (const void**)&from->stack_base, &from->stack_size); #endif rb_thread_t *thread = fiber->cont.saved_ec.thread_ptr; @@ -821,7 +831,8 @@ fiber_initialize_coroutine(rb_fiber_t *fiber, size_t * vm_stack_size) return vm_stack; } -// Release the stack from the fiber, it's execution context, and return it to the fiber pool. +// Release the stack from the fiber, it's execution context, and return it to +// the fiber pool. static void fiber_stack_release(rb_fiber_t * fiber) { -- cgit v1.2.1