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https://github.com/jart/cosmopolitan.git
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Don't relocate file descriptor memory
This change fixes #496 where ASAN spotted a race condition that could happen in multithreaded programs, with more than OPEN_MAX descriptors when using ZipOS or Windows NT, which require tracking open file info and this change fixes that table so it never relocates, thus allowing us to continue to enjoy the benefits of avoiding locks while reading.
This commit is contained in:
Justine Tunney
parent
c3208eb9d5
commit
3265324e00
35 changed files with 297 additions and 152 deletions
250
libc/intrin/memtrack.greg.c
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250
libc/intrin/memtrack.greg.c
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/assert.h"
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#include "libc/intrin/bits.h"
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#include "libc/intrin/likely.h"
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#include "libc/intrin/weaken.h"
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#include "libc/calls/calls.h"
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#include "libc/calls/strace.internal.h"
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#include "libc/dce.h"
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#include "libc/errno.h"
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#include "libc/intrin/asan.internal.h"
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#include "libc/log/libfatal.internal.h"
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#include "libc/log/log.h"
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#include "libc/macros.internal.h"
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#include "libc/mem/mem.h"
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#include "libc/runtime/directmap.internal.h"
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#include "libc/runtime/memtrack.internal.h"
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#include "libc/runtime/runtime.h"
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#include "libc/str/str.h"
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#include "libc/sysv/consts/map.h"
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#include "libc/sysv/consts/prot.h"
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#include "libc/sysv/errfuns.h"
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static void *MoveMemoryIntervals(struct MemoryInterval *d,
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const struct MemoryInterval *s, int n) {
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// asan runtime depends on this function
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int i;
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assert(n >= 0);
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if (d > s) {
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for (i = n; i--;) {
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d[i] = s[i];
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}
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} else {
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for (i = 0; i < n; ++i) {
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d[i] = s[i];
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}
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}
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return d;
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}
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static void RemoveMemoryIntervals(struct MemoryIntervals *mm, int i, int n) {
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// asan runtime depends on this function
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assert(i >= 0);
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assert(i + n <= mm->i);
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MoveMemoryIntervals(mm->p + i, mm->p + i + n, mm->i - (i + n));
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mm->i -= n;
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}
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static bool ExtendMemoryIntervals(struct MemoryIntervals *mm) {
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int prot, flags;
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char *base, *shad;
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size_t gran, size;
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struct DirectMap dm;
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gran = kMemtrackGran;
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base = (char *)kMemtrackStart;
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prot = PROT_READ | PROT_WRITE;
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flags = MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED;
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// TODO(jart): These map handles should not leak across NT fork()
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if (mm->p == mm->s) {
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// TODO(jart): How can we detect ASAN mode under GREG?
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if (1 || IsAsan()) {
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shad = (char *)(((intptr_t)base >> 3) + 0x7fff8000);
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dm = sys_mmap(shad, gran >> 3, prot, flags, -1, 0);
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if (!dm.addr) return false;
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}
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dm = sys_mmap(base, gran, prot, flags, -1, 0);
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if (!dm.addr) return false;
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MoveMemoryIntervals(dm.addr, mm->p, mm->i);
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mm->p = dm.addr;
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mm->n = gran / sizeof(*mm->p);
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} else {
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size = ROUNDUP(mm->n * sizeof(*mm->p), gran);
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base += size;
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if (IsAsan()) {
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shad = (char *)(((intptr_t)base >> 3) + 0x7fff8000);
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dm = sys_mmap(shad, gran >> 3, prot, flags, -1, 0);
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if (!dm.addr) return false;
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}
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dm = sys_mmap(base, gran, prot, flags, -1, 0);
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if (!dm.addr) return false;
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mm->n = (size + gran) / sizeof(*mm->p);
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}
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#if IsModeDbg()
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assert(AreMemoryIntervalsOk(mm));
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#endif
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return true;
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}
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int CreateMemoryInterval(struct MemoryIntervals *mm, int i) {
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// asan runtime depends on this function
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int rc;
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rc = 0;
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assert(i >= 0);
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assert(i <= mm->i);
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assert(mm->n >= 0);
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if (UNLIKELY(mm->i == mm->n) && !ExtendMemoryIntervals(mm)) return enomem();
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MoveMemoryIntervals(mm->p + i + 1, mm->p + i, mm->i++ - i);
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return 0;
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}
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static int PunchHole(struct MemoryIntervals *mm, int x, int y, int i) {
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if (CreateMemoryInterval(mm, i) == -1) return -1;
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mm->p[i + 0].size -= (size_t)(mm->p[i + 0].y - (x - 1)) * FRAMESIZE;
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mm->p[i + 0].y = x - 1;
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mm->p[i + 1].size -= (size_t)((y + 1) - mm->p[i + 1].x) * FRAMESIZE;
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mm->p[i + 1].x = y + 1;
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return 0;
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}
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int ReleaseMemoryIntervals(struct MemoryIntervals *mm, int x, int y,
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void wf(struct MemoryIntervals *, int, int)) {
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unsigned l, r;
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#if IsModeDbg()
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assert(y >= x);
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assert(AreMemoryIntervalsOk(mm));
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#endif
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if (!mm->i) return 0;
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// binary search for the lefthand side
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l = FindMemoryInterval(mm, x);
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if (l == mm->i) return 0;
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if (y < mm->p[l].x) return 0;
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// binary search for the righthand side
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r = FindMemoryInterval(mm, y);
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if (r == mm->i || (r > l && y < mm->p[r].x)) --r;
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assert(r >= l);
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assert(x <= mm->p[r].y);
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// remove the middle of an existing map
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//
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// ----|mmmmmmmmmmmmmmmm|--------- before
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// xxxxx
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// ----|mmmm|-----|mmmmm|--------- after
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//
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// this isn't possible on windows because we track each
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// 64kb segment on that platform using a separate entry
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if (l == r && x > mm->p[l].x && y < mm->p[l].y) {
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return PunchHole(mm, x, y, l);
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}
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// trim the right side of the lefthand map
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//
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// ----|mmmmmmm|-------------- before
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// xxxxx
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// ----|mmmm|----------------- after
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//
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if (x > mm->p[l].x && x <= mm->p[l].y) {
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assert(y >= mm->p[l].y);
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if (IsWindows()) return einval();
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mm->p[l].size -= (size_t)(mm->p[l].y - (x - 1)) * FRAMESIZE;
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mm->p[l].y = x - 1;
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assert(mm->p[l].x <= mm->p[l].y);
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++l;
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}
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// trim the left side of the righthand map
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//
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// ------------|mmmmm|-------- before
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// xxxxx
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// ---------------|mm|-------- after
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//
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if (y >= mm->p[r].x && y < mm->p[r].y) {
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assert(x <= mm->p[r].x);
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if (IsWindows()) return einval();
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mm->p[r].size -= (size_t)((y + 1) - mm->p[r].x) * FRAMESIZE;
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mm->p[r].x = y + 1;
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assert(mm->p[r].x <= mm->p[r].y);
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--r;
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}
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if (l <= r) {
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if (IsWindows() && wf) {
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wf(mm, l, r);
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}
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RemoveMemoryIntervals(mm, l, r - l + 1);
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}
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return 0;
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}
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int TrackMemoryInterval(struct MemoryIntervals *mm, int x, int y, long h,
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int prot, int flags, bool readonlyfile, bool iscow,
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long offset, long size) {
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// asan runtime depends on this function
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unsigned i;
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#if IsModeDbg()
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assert(y >= x);
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assert(AreMemoryIntervalsOk(mm));
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#endif
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i = FindMemoryInterval(mm, x);
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// try to extend the righthand side of the lefthand entry
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// we can't do that if we're tracking independent handles
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// we can't do that if it's a file map with a small size!
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if (i && x == mm->p[i - 1].y + 1 && h == mm->p[i - 1].h &&
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prot == mm->p[i - 1].prot && flags == mm->p[i - 1].flags &&
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mm->p[i - 1].size ==
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(size_t)(mm->p[i - 1].y - mm->p[i - 1].x) * FRAMESIZE + FRAMESIZE) {
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mm->p[i - 1].size += (size_t)(y - mm->p[i - 1].y) * FRAMESIZE;
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mm->p[i - 1].y = y;
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// if we filled the hole then merge the two mappings
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if (i < mm->i && y + 1 == mm->p[i].x && h == mm->p[i].h &&
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prot == mm->p[i].prot && flags == mm->p[i].flags) {
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mm->p[i - 1].y = mm->p[i].y;
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mm->p[i - 1].size += mm->p[i].size;
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RemoveMemoryIntervals(mm, i, 1);
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}
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}
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// try to extend the lefthand side of the righthand entry
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// we can't do that if we're creating a smaller file map!
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else if (i < mm->i && y + 1 == mm->p[i].x && h == mm->p[i].h &&
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prot == mm->p[i].prot && flags == mm->p[i].flags &&
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size == (size_t)(y - x) * FRAMESIZE + FRAMESIZE) {
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mm->p[i].size += (size_t)(mm->p[i].x - x) * FRAMESIZE;
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mm->p[i].x = x;
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}
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// otherwise, create a new entry and memmove the items
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else {
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if (CreateMemoryInterval(mm, i) == -1) return -1;
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mm->p[i].x = x;
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mm->p[i].y = y;
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mm->p[i].h = h;
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mm->p[i].prot = prot;
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mm->p[i].flags = flags;
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mm->p[i].offset = offset;
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mm->p[i].size = size;
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mm->p[i].iscow = iscow;
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mm->p[i].readonlyfile = readonlyfile;
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}
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return 0;
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}
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