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Fix pthread stacks with larger guard size

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Justine Tunney 2022-09-09 06:19:05 -07:00
parent 1db76c288e
commit e97f1a99cf
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GPG key ID: BE714B4575D6E328
10 changed files with 68 additions and 42 deletions
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53
libc/thread/pthread_create.c
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@ -96,8 +96,8 @@ static int FixupCustomStackOnOpenbsd(pthread_attr_t *attr) {
n = ROUNDDOWN(n, PAGESIZE);
e = errno;
if (__sys_mmap((void *)y, n, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANON_OPENBSD | MAP_STACK_OPENBSD, -1, 0,
0) != MAP_FAILED) {
MAP_PRIVATE | MAP_FIXED | MAP_ANON_OPENBSD | MAP_STACK_OPENBSD,
-1, 0, 0) == (void *)y) {
attr->stackaddr = (void *)y;
attr->stacksize = n;
return 0;
@ -215,8 +215,28 @@ int pthread_create(pthread_t *thread, const pthread_attr_t *attr,
_pthread_free(pt);
return EINVAL;
}
pt->attr.stackaddr = mmap(0, pt->attr.stacksize, PROT_READ | PROT_WRITE,
MAP_STACK | MAP_ANONYMOUS, -1, 0);
if (pt->attr.guardsize == PAGESIZE) {
// user is wisely using smaller stacks with default guard size
pt->attr.stackaddr = mmap(0, pt->attr.stacksize, PROT_READ | PROT_WRITE,
MAP_STACK | MAP_ANONYMOUS, -1, 0);
} else {
// user is tuning things, performance may suffer
pt->attr.stackaddr = mmap(0, pt->attr.stacksize, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (pt->attr.stackaddr != MAP_FAILED) {
if (IsOpenbsd() &&
__sys_mmap(
pt->attr.stackaddr, pt->attr.stacksize, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_FIXED | MAP_ANON_OPENBSD | MAP_STACK_OPENBSD,
-1, 0, 0) != pt->attr.stackaddr) {
notpossible;
}
if (pt->attr.guardsize && !IsWindows() &&
mprotect(pt->attr.stackaddr, pt->attr.guardsize, PROT_NONE)) {
notpossible;
}
}
}
if (pt->attr.stackaddr == MAP_FAILED) {
rc = errno;
_pthread_free(pt);
@ -227,27 +247,8 @@ int pthread_create(pthread_t *thread, const pthread_attr_t *attr,
return EAGAIN;
}
}
// mmap(MAP_STACK) creates a 4096 guard by default
if (pt->attr.guardsize != PAGESIZE) {
if (pt->attr.guardsize) {
// user requested special guard size
rc = mprotect(pt->attr.stackaddr, pt->attr.guardsize, PROT_NONE);
} else {
// user explicitly disabled guard page
rc = mprotect(pt->attr.stackaddr, PAGESIZE, PROT_READ | PROT_WRITE);
}
if (rc) {
notpossible;
}
}
if (IsAsan()) {
if (pt->attr.guardsize) {
__asan_poison(pt->attr.stackaddr, pt->attr.guardsize,
kAsanStackOverflow);
}
__asan_poison((char *)pt->attr.stackaddr + pt->attr.stacksize -
16 /* openbsd:stackbound */,
16, kAsanStackOverflow);
if (IsAsan() && pt->attr.guardsize) {
__asan_poison(pt->attr.stackaddr, pt->attr.guardsize, kAsanStackOverflow);
}
}
@ -267,7 +268,7 @@ int pthread_create(pthread_t *thread, const pthread_attr_t *attr,
// launch PosixThread(pt) in new thread
if (clone(PosixThread, pt->attr.stackaddr,
pt->attr.stacksize - 16 /* openbsd:stackbound */,
pt->attr.stacksize - (IsOpenbsd() ? 16 : 0),
CLONE_VM | CLONE_THREAD | CLONE_FS | CLONE_FILES | CLONE_SIGHAND |
CLONE_SETTLS | CLONE_PARENT_SETTID | CLONE_CHILD_SETTID |
CLONE_CHILD_CLEARTID,