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99 lines
2.8 KiB
99 lines
2.8 KiB
From d60fc73a370c64209bd0ae6fc6d002f55be6eac9 Mon Sep 17 00:00:00 2001 |
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From: Kevin Atkinson <kevina@gnu.org> |
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Date: Sat, 21 Dec 2019 20:32:47 +0000 |
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Subject: [PATCH] objstack: assert that the alloc size will fit within a chunk |
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to prevent a buffer overflow |
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Bug found using OSS-Fuze. |
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--- |
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common/objstack.hpp | 18 ++++++++++++++---- |
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1 file changed, 14 insertions(+), 4 deletions(-) |
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diff --git a/common/objstack.hpp b/common/objstack.hpp |
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index 3997bf7..bd97ccd 100644 |
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--- a/common/objstack.hpp |
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+++ b/common/objstack.hpp |
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@@ -5,6 +5,7 @@ |
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#include "parm_string.hpp" |
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#include <stdlib.h> |
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#include <assert.h> |
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+#include <stddef.h> |
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namespace acommon { |
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@@ -26,6 +27,12 @@ class ObjStack |
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byte * temp_end; |
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void setup_chunk(); |
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void new_chunk(); |
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+ bool will_overflow(size_t sz) const { |
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+ return offsetof(Node,data) + sz > chunk_size; |
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+ } |
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+ void check_size(size_t sz) { |
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+ assert(!will_overflow(sz)); |
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+ } |
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ObjStack(const ObjStack &); |
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void operator=(const ObjStack &); |
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@@ -56,7 +63,7 @@ public: |
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void * alloc_bottom(size_t size) { |
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byte * tmp = bottom; |
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bottom += size; |
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- if (bottom > top) {new_chunk(); tmp = bottom; bottom += size;} |
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+ if (bottom > top) {check_size(size); new_chunk(); tmp = bottom; bottom += size;} |
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return tmp; |
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} |
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// This alloc_bottom will insure that the object is aligned based on the |
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@@ -66,7 +73,7 @@ public: |
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align_bottom(align); |
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byte * tmp = bottom; |
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bottom += size; |
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- if (bottom > top) {new_chunk(); goto loop;} |
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+ if (bottom > top) {check_size(size); new_chunk(); goto loop;} |
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return tmp; |
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} |
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char * dup_bottom(ParmString str) { |
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@@ -79,7 +86,7 @@ public: |
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// always be aligned as such. |
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void * alloc_top(size_t size) { |
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top -= size; |
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- if (top < bottom) {new_chunk(); top -= size;} |
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+ if (top < bottom) {check_size(size); new_chunk(); top -= size;} |
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return top; |
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} |
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// This alloc_top will insure that the object is aligned based on |
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@@ -88,7 +95,7 @@ public: |
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{loop: |
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top -= size; |
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align_top(align); |
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- if (top < bottom) {new_chunk(); goto loop;} |
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+ if (top < bottom) {check_size(size); new_chunk(); goto loop;} |
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return top; |
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} |
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char * dup_top(ParmString str) { |
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@@ -117,6 +124,7 @@ public: |
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void * alloc_temp(size_t size) { |
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temp_end = bottom + size; |
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if (temp_end > top) { |
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+ check_size(size); |
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new_chunk(); |
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temp_end = bottom + size; |
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} |
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@@ -131,6 +139,7 @@ public: |
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} else { |
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size_t s = temp_end - bottom; |
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byte * p = bottom; |
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+ check_size(size); |
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new_chunk(); |
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memcpy(bottom, p, s); |
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temp_end = bottom + size; |
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@@ -150,6 +159,7 @@ public: |
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} else { |
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size_t s = temp_end - bottom; |
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byte * p = bottom; |
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+ check_size(size); |
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new_chunk(); |
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memcpy(bottom, p, s); |
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temp_end = bottom + size; |
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-- |
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2.31.1 |
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