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Fix corner case in Linux stack mappings

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We need to make sure no existing mappings exist between the
MAP_GROWSDOWN page and the guard page, since otherwise it's
not going to be able to grow down thus causing difficult to
troubleshoot failures.
This commit is contained in:
Justine Tunney 2022-10-03 13:43:52 -07:00
parent 6ba3b448f3
commit 3b4fcd8575
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GPG key ID: BE714B4575D6E328
9 changed files with 14 additions and 16 deletions
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2
libc/integral/normalize.inc
View file

@ -68,7 +68,7 @@
/* TODO(jart): Remove this in favor of GetStackSize() */
#if defined(COSMO) && (defined(MODE_DBG) || defined(__SANITIZE_ADDRESS__))
#define STACKSIZE 524288 /* 512kb stack */
#define STACKSIZE 262144 /* 256kb stack */
#elif defined(COSMO)
#define STACKSIZE 65536 /* 64kb stack */
#else

2
libc/intrin/stracef.greg.c
View file

@ -16,8 +16,8 @@
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/intrin/strace.internal.h"
#include "libc/intrin/kprintf.h"
#include "libc/intrin/strace.internal.h"
#include "libc/runtime/runtime.h"
privileged void __stracef(const char *fmt, ...) {

9
libc/runtime/mmap.c
View file

@ -361,6 +361,10 @@ static noasan inline void *Mmap(void *addr, size_t size, int prot, int flags,
f |= MAP_STACK_openbsd;
needguard = true;
} else if (IsLinux()) {
// make sure there's no existing stuff existing between our stack
// starting page and the bottom guard page, since that would stop
// our stack page from growing down.
_npassert(!sys_munmap(p, size));
// by default MAP_GROWSDOWN will auto-allocate 10mb of pages. it's
// supposed to stop growing if an adjacent allocation exists, to
// prevent your stacks from overlapping on each other. we're not
@ -376,8 +380,9 @@ static noasan inline void *Mmap(void *addr, size_t size, int prot, int flags,
.addr == MAP_FAILED) {
return MAP_FAILED;
}
sys_mmap(p, PAGESIZE, PROT_NONE, MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS,
-1, 0);
_npassert(sys_mmap(p, PAGESIZE, PROT_NONE,
MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0)
.addr == p);
dm.addr = p;
return FinishMemory(p, size, prot, flags, fd, off, f, x, n, dm);
} else {

2
libc/runtime/mprotect.c
View file

@ -16,12 +16,12 @@
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/intrin/strace.internal.h"
#include "libc/calls/syscall-sysv.internal.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/intrin/describeflags.internal.h"
#include "libc/intrin/likely.h"
#include "libc/intrin/strace.internal.h"
#include "libc/runtime/internal.h"
#include "libc/sysv/consts/prot.h"

3
libc/stdio/fflush.internal.h
View file

@ -1,8 +1,9 @@
#ifndef COSMOPOLITAN_LIBC_STDIO_FFLUSH_H_
#define COSMOPOLITAN_LIBC_STDIO_FFLUSH_H_
#include "libc/intrin/nopl.internal.h"
#include "libc/thread/thread.h"
#include "libc/stdio/stdio.h"
#include "libc/thread/thread.h"
#include "libc/thread/tls.h"
#if !(__ASSEMBLER__ + __LINKER__ + 0)
COSMOPOLITAN_C_START_

2
libc/sysv/consts.sh
View file

@ -579,8 +579,6 @@ syscon sicode SYS_USER_DISPATCH 2 -1 -1 -1 -1 -1 # SIGSYS; syscall
# sigaltstack() values
#
# group name GNU/Systemd XNU's Not UNIX! FreeBSD OpenBSD NetBSD The New Technology Commentary
syscon ss SIGSTKSZ 8192 131072 34816 28672 28672 8192 # overlaid with FRAMESIZE; you need to #undef SIGSTKSZ to access this symbol
syscon ss MINSIGSTKSZ 2048 32768 2048 12288 8192 2048 # overlaid with 32768; you need to #undef MINSIGSTKSZ to access this symbol
syscon ss SS_ONSTACK 1 1 1 1 1 1 # unix consensus
syscon ss SS_DISABLE 2 4 4 4 4 2 # bsd consensus

2
libc/sysv/consts/MINSIGSTKSZ.s
View file

@ -1,2 +0,0 @@
.include "o/libc/sysv/consts/syscon.internal.inc"
.syscon ss,MINSIGSTKSZ,2048,32768,2048,12288,8192,2048

2
libc/sysv/consts/SIGSTKSZ.s
View file

@ -1,2 +0,0 @@
.include "o/libc/sysv/consts/syscon.internal.inc"
.syscon ss,SIGSTKSZ,8192,131072,34816,28672,28672,8192

6
libc/sysv/consts/ss.h
View file

@ -3,15 +3,13 @@
#if !(__ASSEMBLER__ + __LINKER__ + 0)
COSMOPOLITAN_C_START_
extern const size_t SIGSTKSZ;
extern const size_t MINSIGSTKSZ;
extern const int SS_DISABLE;
COSMOPOLITAN_C_END_
#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
#define SIGSTKSZ FRAMESIZE
#define MINSIGSTKSZ 32768
#define SIGSTKSZ 32768
#define MINSIGSTKSZ 32768 /* xnu defines the highest minimum */
#define SS_ONSTACK 1
#define SS_DISABLE SS_DISABLE