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Mark asan fake stacks during machine stack marking

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ASAN leaves a pointer to the fake frame on the stack; we can use the
__asan_addr_is_in_fake_stack API to work out the extent of the fake
stack and thus mark any VALUEs contained therein.

[Bug #20001]
This commit is contained in:
KJ Tsanaktsidis 2023-11-12 16:19:31 +11:00
parent bdafad8790
commit d10bc3a2b8
8 changed files with 157 additions and 7 deletions
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63
internal/sanitizers.h
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@ -213,4 +213,67 @@ asan_get_real_stack_addr(void* slot)
return addr ? addr : slot;
}
/*!
* Gets the current thread's fake stack handle, which can be passed into get_fake_stack_extents
*
* \retval An opaque value which can be passed to asan_get_fake_stack_extents
*/
static inline void *
asan_get_thread_fake_stack_handle(void)
{
return __asan_get_current_fake_stack();
}
/*!
* Checks if the given VALUE _actually_ represents a pointer to an ASAN fake stack.
*
* If the given slot _is_ actually a reference to an ASAN fake stack, and that fake stack
* contains the real values for the passed-in range of machine stack addresses, returns true
* and the range of the fake stack through the outparams.
*
* Otherwise, returns false, and sets the outparams to NULL.
*
* Note that this function expects "start" to be > "end" on downward-growing stack architectures;
*
* \param[in] thread_fake_stack_handle The asan fake stack reference for the thread we're scanning
* \param[in] slot The value on the machine stack we want to inspect
* \param[in] machine_stack_start The extents of the real machine stack on which slot lives
* \param[in] machine_stack_end The extents of the real machine stack on which slot lives
* \param[out] fake_stack_start_out The extents of the fake stack which contains real VALUEs
* \param[out] fake_stack_end_out The extents of the fake stack which contains real VALUEs
* \return Whether slot is a pointer to a fake stack for the given machine stack range
*/
static inline bool
asan_get_fake_stack_extents(void *thread_fake_stack_handle, VALUE slot,
void *machine_stack_start, void *machine_stack_end,
void **fake_stack_start_out, void **fake_stack_end_out)
{
/* the ifdef is needed here to suppress a warning about fake_frame_{start/end} being
uninitialized if __asan_addr_is_in_fake_stack is an empty macro */
#ifdef RUBY_ASAN_ENABLED
void *fake_frame_start;
void *fake_frame_end;
void *real_stack_frame = __asan_addr_is_in_fake_stack(
thread_fake_stack_handle, (void *)slot, &fake_frame_start, &fake_frame_end
);
if (real_stack_frame) {
bool in_range;
#if STACK_GROW_DIRECTION < 0
in_range = machine_stack_start >= real_stack_frame && real_stack_frame >= machine_stack_end;
#else
in_range = machine_stack_start <= real_stack_frame && real_stack_frame <= machine_stack_end;
#endif
if (in_range) {
*fake_stack_start_out = fake_frame_start;
*fake_stack_end_out = fake_frame_end;
return true;
}
}
#endif
*fake_stack_start_out = 0;
*fake_stack_end_out = 0;
return false;
}
#endif /* INTERNAL_SANITIZERS_H */