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96 lines
3.3 KiB
Diff
96 lines
3.3 KiB
Diff
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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Daniel Micay <danielmicay@gmail.com>
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Date: Thu, 3 Dec 2015 12:58:31 -0500
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Subject: [PATCH] add memory protection for pthread_atfork handlers
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Signed-off-by: anupritaisno1 <www.anuprita804@gmail.com>
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---
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libc/bionic/pthread_atfork.cpp | 34 ++++++++++++++++++++++++++++++++--
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1 file changed, 32 insertions(+), 2 deletions(-)
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diff --git a/libc/bionic/pthread_atfork.cpp b/libc/bionic/pthread_atfork.cpp
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index 6306052ee..d59f3ae54 100644
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--- a/libc/bionic/pthread_atfork.cpp
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+++ b/libc/bionic/pthread_atfork.cpp
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@@ -47,6 +47,7 @@ struct atfork_t {
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};
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static atfork_t* pool;
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+static atfork_t* page_list;
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class atfork_list_t {
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public:
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@@ -160,13 +161,22 @@ void __bionic_atfork_run_parent() {
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// __register_atfork is the name used by glibc
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extern "C" int __register_atfork(void (*prepare)(void), void (*parent)(void),
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void(*child)(void), void* dso) {
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+ size_t page_size = getpagesize();
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+
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pthread_mutex_lock(&g_atfork_list_mutex);
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+ for (atfork_t* page_it = page_list; page_it; page_it = page_it->next) {
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+ mprotect(page_it, page_size, PROT_READ|PROT_WRITE);
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+ }
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+
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if (!pool) {
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- size_t page_size = getpagesize();
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char* page = static_cast<char*>(mmap(NULL, page_size, PROT_READ|PROT_WRITE,
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MAP_ANONYMOUS|MAP_PRIVATE, -1, 0));
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if (page == MAP_FAILED) {
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+ for (atfork_t* page_it = page_list; page_it; page_it = page_it->next) {
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+ mprotect(page_it, page_size, PROT_READ);
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+ }
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+
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pthread_mutex_unlock(&g_atfork_list_mutex);
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return ENOMEM;
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}
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@@ -174,11 +184,15 @@ extern "C" int __register_atfork(void (*prepare)(void), void (*parent)(void),
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prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, page, page_size,
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"atfork handlers");
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- for (char* it = page; it < page + page_size - sizeof(atfork_t); it += sizeof(atfork_t)) {
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+ for (char* it = page + sizeof(atfork_t); it < page + page_size - sizeof(atfork_t); it += sizeof(atfork_t)) {
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atfork_t* node = reinterpret_cast<atfork_t*>(it);
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node->next = pool;
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pool = node;
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}
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+
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+ atfork_t* page_node = reinterpret_cast<atfork_t*>(page);
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+ page_node->next = page_list;
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+ page_list = page_node;
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}
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atfork_t* entry = pool;
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@@ -191,6 +205,10 @@ extern "C" int __register_atfork(void (*prepare)(void), void (*parent)(void),
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g_atfork_list.push_back(entry);
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+ for (atfork_t* page_it = page_list; page_it; page_it = page_it->next) {
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+ mprotect(page_it, page_size, PROT_READ);
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+ }
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+
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pthread_mutex_unlock(&g_atfork_list_mutex);
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return 0;
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@@ -198,8 +216,20 @@ extern "C" int __register_atfork(void (*prepare)(void), void (*parent)(void),
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extern "C" __LIBC_HIDDEN__ void __unregister_atfork(void* dso) {
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pthread_mutex_lock(&g_atfork_list_mutex);
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+
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+ size_t page_size = getpagesize();
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+
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+ for (atfork_t* page_it = page_list; page_it; page_it = page_it->next) {
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+ mprotect(page_it, page_size, PROT_READ|PROT_WRITE);
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+ }
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+
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g_atfork_list.remove_if([&](const atfork_t* entry) {
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return entry->dso_handle == dso;
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});
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+
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+ for (atfork_t* page_it = page_list; page_it; page_it = page_it->next) {
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+ mprotect(page_it, page_size, PROT_READ);
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+ }
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+
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pthread_mutex_unlock(&g_atfork_list_mutex);
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}
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