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81 lines
2.0 KiB
Diff
81 lines
2.0 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Daniel Micay <danielmicay@gmail.com>
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Date: Sat, 7 Feb 2015 20:14:24 -0500
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Subject: [PATCH] add memory protection for at_quick_exit
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---
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.../lib/libc/stdlib/quick_exit.c | 41 ++++++++++++++++---
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1 file changed, 36 insertions(+), 5 deletions(-)
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diff --git a/libc/upstream-freebsd/lib/libc/stdlib/quick_exit.c b/libc/upstream-freebsd/lib/libc/stdlib/quick_exit.c
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index ef8cdb1b4..b23d8642a 100644
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--- a/libc/upstream-freebsd/lib/libc/stdlib/quick_exit.c
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+++ b/libc/upstream-freebsd/lib/libc/stdlib/quick_exit.c
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@@ -28,6 +28,10 @@
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#include <stdlib.h>
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#include <pthread.h>
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+#include <sys/mman.h>
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+#include <unistd.h>
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+
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+#include "private/bionic_prctl.h"
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/**
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* Linked list of quick exit handlers. This is simpler than the atexit()
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@@ -39,6 +43,10 @@ struct quick_exit_handler {
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void (*cleanup)(void);
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};
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+static struct quick_exit_handler *pool_page;
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+static struct quick_exit_handler *pool;
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+static size_t pool_size;
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+
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/**
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* Lock protecting the handlers list.
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*/
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@@ -51,16 +59,39 @@ static struct quick_exit_handler *handlers;
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int
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at_quick_exit(void (*func)(void))
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{
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+ size_t page_size = getpagesize();
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struct quick_exit_handler *h;
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-
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- h = malloc(sizeof(*h));
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- if (NULL == h)
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- return (1);
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- h->cleanup = func;
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pthread_mutex_lock(&atexit_mutex);
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+
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+ if (pool_size < sizeof(*h)) {
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+ void *ptr = mmap(NULL, page_size, PROT_READ|PROT_WRITE,
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+ MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
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+ if (ptr == MAP_FAILED) {
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+ pthread_mutex_unlock(&atexit_mutex);
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+ return (1);
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+ }
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+ prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, ptr, page_size,
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+ "at_quick_exit handlers");
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+ pool_page = pool = ptr;
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+ pool_size = page_size;
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+ } else {
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+ if (mprotect(pool_page, page_size, PROT_READ|PROT_WRITE)) {
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+ pthread_mutex_unlock(&atexit_mutex);
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+ return (1);
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+ }
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+ }
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+
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+ h = pool++;
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+ pool_size -= sizeof(*h);
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+
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+ h->cleanup = func;
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+
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h->next = handlers;
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handlers = h;
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+
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+ mprotect(pool_page, page_size, PROT_READ);
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+
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pthread_mutex_unlock(&atexit_mutex);
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return (0);
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}
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