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ucontext: annotate coroutine stack for ASAN

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It helps ASAN to detect more leaks on coroutine stacks, and to get rid
of some extra warnings.

Before:

tests/test-coroutine -p
/basic/lifecycle
/basic/lifecycle: ==20781==WARNING: ASan doesn't fully support
makecontext/swapcontext functions and may produce false positives in
some cases!
==20781==WARNING: ASan is ignoring requested __asan_handle_no_return:
stack top: 0x7ffcb184d000; bottom 0x7ff6c4cfd000; size: 0x0005ecb50000
(25446121472)
False positive error reports may follow
For details see https://github.com/google/sanitizers/issues/189
OK

After:

tests/test-coroutine -p /basic/lifecycle
/basic/lifecycle: ==21110==WARNING: ASan doesn't fully support
makecontext/swapcontext functions and may produce false positives in
some cases!
OK

A similar work would need to be done for sigaltstack & windows fibers
to have similar coverage. Since ucontext is preferred, I didn't bother
checking the other coroutine implementations for now.

Update travis to fix the build with ASAN annotations.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20180116151152.4040-4-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Marc-André Lureau
2018-01-16 16:11:52 +01:00
committed by Paolo Bonzini
parent 247724cb30
commit d83414e1fd
4 changed files with 84 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

48
util/coroutine-ucontext.c
View File

@ -31,6 +31,13 @@
#include <valgrind/valgrind.h>
#endif
#if defined(__SANITIZE_ADDRESS__) || __has_feature(address_sanitizer)
#ifdef CONFIG_ASAN_IFACE_FIBER
#define CONFIG_ASAN 1
#include <sanitizer/asan_interface.h>
#endif
#endif
typedef struct {
Coroutine base;
void *stack;
@ -59,11 +66,37 @@ union cc_arg {
int i[2];
};
static void finish_switch_fiber(void *fake_stack_save)
{
#ifdef CONFIG_ASAN
const void *bottom_old;
size_t size_old;
__sanitizer_finish_switch_fiber(fake_stack_save, &bottom_old, &size_old);
if (!leader.stack) {
leader.stack = (void *)bottom_old;
leader.stack_size = size_old;
}
#endif
}
static void start_switch_fiber(void **fake_stack_save,
const void *bottom, size_t size)
{
#ifdef CONFIG_ASAN
__sanitizer_start_switch_fiber(fake_stack_save, bottom, size);
#endif
}
static void coroutine_trampoline(int i0, int i1)
{
union cc_arg arg;
CoroutineUContext *self;
Coroutine *co;
void *fake_stack_save = NULL;
finish_switch_fiber(NULL);
arg.i[0] = i0;
arg.i[1] = i1;
@ -72,9 +105,13 @@ static void coroutine_trampoline(int i0, int i1)
/* Initialize longjmp environment and switch back the caller */
if (!sigsetjmp(self->env, 0)) {
start_switch_fiber(&fake_stack_save,
leader.stack, leader.stack_size);
siglongjmp(*(sigjmp_buf *)co->entry_arg, 1);
}
finish_switch_fiber(fake_stack_save);
while (true) {
co->entry(co->entry_arg);
qemu_coroutine_switch(co, co->caller, COROUTINE_TERMINATE);
@ -87,6 +124,7 @@ Coroutine *qemu_coroutine_new(void)
ucontext_t old_uc, uc;
sigjmp_buf old_env;
union cc_arg arg = {0};
void *fake_stack_save = NULL;
/* The ucontext functions preserve signal masks which incurs a
* system call overhead. sigsetjmp(buf, 0)/siglongjmp() does not
@ -122,8 +160,12 @@ Coroutine *qemu_coroutine_new(void)
/* swapcontext() in, siglongjmp() back out */
if (!sigsetjmp(old_env, 0)) {
start_switch_fiber(&fake_stack_save, co->stack, co->stack_size);
swapcontext(&old_uc, &uc);
}
finish_switch_fiber(fake_stack_save);
return &co->base;
}
@ -169,13 +211,19 @@ qemu_coroutine_switch(Coroutine *from_, Coroutine *to_,
CoroutineUContext *from = DO_UPCAST(CoroutineUContext, base, from_);
CoroutineUContext *to = DO_UPCAST(CoroutineUContext, base, to_);
int ret;
void *fake_stack_save = NULL;
current = to_;
ret = sigsetjmp(from->env, 0);
if (ret == 0) {
start_switch_fiber(action == COROUTINE_TERMINATE ?
NULL : &fake_stack_save, to->stack, to->stack_size);
siglongjmp(to->env, action);
}
finish_switch_fiber(fake_stack_save);
return ret;
}