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75 lines
2.1 KiB
Diff
75 lines
2.1 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: Sun, 8 Feb 2015 01:18:54 -0500
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Subject: [PATCH] replace brk and sbrk with stubs
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Pretend that there is never room to grow the heap in order to prevent
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usage of these unsafe legacy functions. There are likely no users of
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these in practice as it is inherently broken to use them outside of
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malloc.
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---
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libc/bionic/brk.cpp | 48 ++++++++-------------------------------------
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1 file changed, 8 insertions(+), 40 deletions(-)
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diff --git a/libc/bionic/brk.cpp b/libc/bionic/brk.cpp
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index 566c33a7a..ef9305513 100644
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--- a/libc/bionic/brk.cpp
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+++ b/libc/bionic/brk.cpp
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@@ -29,48 +29,16 @@
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#include <errno.h>
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#include <unistd.h>
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-#if defined(__LP64__)
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-static void* __bionic_brk;
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-#else
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-void* __bionic_brk; // Accidentally exported by the NDK.
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+#if !defined(__LP64__)
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+void* __bionic_brk = reinterpret_cast<void*>(-1); // Accidentally exported by the NDK.
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#endif
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-extern "C" void* __brk(void* __addr);
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-
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-int brk(void* end_data) {
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- __bionic_brk = __brk(end_data);
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- if (__bionic_brk < end_data) {
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- errno = ENOMEM;
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- return -1;
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- }
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- return 0;
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+int brk(void*) {
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+ errno = ENOMEM;
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+ return -1;
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}
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-void* sbrk(ptrdiff_t increment) {
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- // Initialize __bionic_brk if necessary.
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- if (__bionic_brk == nullptr) {
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- __bionic_brk = __brk(nullptr);
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- }
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-
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- // Don't ask the kernel if we already know the answer.
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- if (increment == 0) {
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- return __bionic_brk;
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- }
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-
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- // Avoid overflow.
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- uintptr_t old_brk = reinterpret_cast<uintptr_t>(__bionic_brk);
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- if ((increment > 0 && static_cast<uintptr_t>(increment) > (UINTPTR_MAX - old_brk)) ||
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- (increment < 0 && static_cast<uintptr_t>(-increment) > old_brk)) {
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- errno = ENOMEM;
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- return reinterpret_cast<void*>(-1);
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- }
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-
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- void* desired_brk = reinterpret_cast<void*>(old_brk + increment);
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- __bionic_brk = __brk(desired_brk);
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- if (__bionic_brk < desired_brk) {
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- errno = ENOMEM;
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- return reinterpret_cast<void*>(-1);
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- }
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-
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- return reinterpret_cast<void*>(old_brk);
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+void* sbrk(ptrdiff_t) {
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+ errno = ENOMEM;
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+ return reinterpret_cast<void*>(-1);
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}
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