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Remove alternate stack with sigaltstack before unmapping it.

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Also reuse existing signal stack if already set, this is especially
useful when working with sanitizers that configure alternate stack
themselves.
This commit is contained in:
Tomasz Miąsko
2016-02-15 15:45:52 +01:00
parent 7ce4afbdda
commit 77922b817e
3 changed files with 69 additions and 6 deletions
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29
src/libstd/sys/unix/stack_overflow.rs
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@@ -46,7 +46,7 @@ mod imp {
use super::Handler;
use mem;
use ptr;
use libc::{sigaltstack, SIGSTKSZ};
use libc::{sigaltstack, SIGSTKSZ, SS_DISABLE};
use libc::{sigaction, SIGBUS, SIG_DFL,
SA_SIGINFO, SA_ONSTACK, sighandler_t};
use libc;
@@ -169,13 +169,32 @@ mod imp {
}
pub unsafe fn make_handler() -> Handler {
let stack = get_stack();
sigaltstack(&stack, ptr::null_mut());
Handler { _data: stack.ss_sp as *mut libc::c_void }
let mut stack = mem::zeroed();
sigaltstack(ptr::null(), &mut stack);
// Configure alternate signal stack, if one is not already set.
if stack.ss_flags & SS_DISABLE != 0 {
stack = get_stack();
sigaltstack(&stack, ptr::null_mut());
Handler { _data: stack.ss_sp as *mut libc::c_void }
} else {
Handler { _data: ptr::null_mut() }
}
}
pub unsafe fn drop_handler(handler: &mut Handler) {
munmap(handler._data, SIGSTKSZ);
if !handler._data.is_null() {
let stack = libc::stack_t {
ss_sp: ptr::null_mut(),
ss_flags: SS_DISABLE,
// Workaround for bug in MacOS implementation of sigaltstack
// UNIX2003 which returns ENOMEM when disabling a stack while
// passing ss_size smaller than MINSIGSTKSZ. According to POSIX
// both ss_sp and ss_size should be ignored in this case.
ss_size: SIGSTKSZ,
};
sigaltstack(&stack, ptr::null_mut());
munmap(handler._data, SIGSTKSZ);
}
}
}