1From 0718b375425aad8e54e1150313b862e4c6fd324a Mon Sep 17 00:00:00 2001 2From: Kevin Atkinson <kevina@gnu.org> 3Date: Sat, 21 Dec 2019 20:32:47 +0000 4Subject: [PATCH] objstack: assert that the alloc size will fit within a chunk 5 to prevent a buffer overflow 6 7Bug found using OSS-Fuze. 8 9Upstream-Status: Backport 10[https://github.com/gnuaspell/aspell/commit/0718b375425aad8e54e1150313b862e4c6fd324a] 11CVE: CVE-2019-25051 12Signed-off-by: Chee Yang Lee <chee.yang.lee@intel.com> 13--- 14 common/objstack.hpp | 18 ++++++++++++++---- 15 1 file changed, 14 insertions(+), 4 deletions(-) 16 17diff --git a/common/objstack.hpp b/common/objstack.hpp 18index 3997bf7..bd97ccd 100644 19--- a/common/objstack.hpp 20+++ b/common/objstack.hpp 21@@ -5,6 +5,7 @@ 22 #include "parm_string.hpp" 23 #include <stdlib.h> 24 #include <assert.h> 25+#include <stddef.h> 26 27 namespace acommon { 28 29@@ -26,6 +27,12 @@ class ObjStack 30 byte * temp_end; 31 void setup_chunk(); 32 void new_chunk(); 33+ bool will_overflow(size_t sz) const { 34+ return offsetof(Node,data) + sz > chunk_size; 35+ } 36+ void check_size(size_t sz) { 37+ assert(!will_overflow(sz)); 38+ } 39 40 ObjStack(const ObjStack &); 41 void operator=(const ObjStack &); 42@@ -56,7 +63,7 @@ class ObjStack 43 void * alloc_bottom(size_t size) { 44 byte * tmp = bottom; 45 bottom += size; 46- if (bottom > top) {new_chunk(); tmp = bottom; bottom += size;} 47+ if (bottom > top) {check_size(size); new_chunk(); tmp = bottom; bottom += size;} 48 return tmp; 49 } 50 // This alloc_bottom will insure that the object is aligned based on the 51@@ -66,7 +73,7 @@ class ObjStack 52 align_bottom(align); 53 byte * tmp = bottom; 54 bottom += size; 55- if (bottom > top) {new_chunk(); goto loop;} 56+ if (bottom > top) {check_size(size); new_chunk(); goto loop;} 57 return tmp; 58 } 59 char * dup_bottom(ParmString str) { 60@@ -79,7 +86,7 @@ class ObjStack 61 // always be aligned as such. 62 void * alloc_top(size_t size) { 63 top -= size; 64- if (top < bottom) {new_chunk(); top -= size;} 65+ if (top < bottom) {check_size(size); new_chunk(); top -= size;} 66 return top; 67 } 68 // This alloc_top will insure that the object is aligned based on 69@@ -88,7 +95,7 @@ class ObjStack 70 {loop: 71 top -= size; 72 align_top(align); 73- if (top < bottom) {new_chunk(); goto loop;} 74+ if (top < bottom) {check_size(size); new_chunk(); goto loop;} 75 return top; 76 } 77 char * dup_top(ParmString str) { 78@@ -117,6 +124,7 @@ class ObjStack 79 void * alloc_temp(size_t size) { 80 temp_end = bottom + size; 81 if (temp_end > top) { 82+ check_size(size); 83 new_chunk(); 84 temp_end = bottom + size; 85 } 86@@ -131,6 +139,7 @@ class ObjStack 87 } else { 88 size_t s = temp_end - bottom; 89 byte * p = bottom; 90+ check_size(size); 91 new_chunk(); 92 memcpy(bottom, p, s); 93 temp_end = bottom + size; 94@@ -150,6 +159,7 @@ class ObjStack 95 } else { 96 size_t s = temp_end - bottom; 97 byte * p = bottom; 98+ check_size(size); 99 new_chunk(); 100 memcpy(bottom, p, s); 101 temp_end = bottom + size; 102