Fix obscure SEGV

GJDuck · GJDuck · commit b59068c1a970 · 2022-11-30T10:37:46.000+08:00
(requires invalid JSON to trigger)
diff --git a/Makefile b/Makefile
@@ -37,10 +37,14 @@ release: $(E9PATCH_OBJS)
 	$(CXX) $(CXXFLAGS) $(E9PATCH_OBJS) -o e9patch $(LDFLAGS)
 	strip e9patch
 
-debug: CXXFLAGS += -O0 -g -fsanitize=address
+debug: CXXFLAGS += -O0 -g
 debug: $(E9PATCH_OBJS)
 	$(CXX) $(CXXFLAGS) $(E9PATCH_OBJS) -o e9patch
 
+sanitize: CXXFLAGS += -O0 -g -fsanitize=address
+sanitize: $(E9PATCH_OBJS)
+	$(CXX) $(CXXFLAGS) $(E9PATCH_OBJS) -o e9patch
+
 tool: CXXFLAGS += -O2 -I src/e9tool/ -I zydis/include/ \
     -I zydis/dependencies/zycore/include/ -Wno-unused-function
 tool: $(E9TOOL_OBJS) 
@@ -49,9 +53,15 @@ tool: $(E9TOOL_OBJS)
 	strip e9tool
 
 tool.debug: CXXFLAGS += -O0 -g -I src/e9tool/ -I zydis/include/ \
+    -I zydis/dependencies/zycore/include/ -Wno-unused-function
+tool.debug: $(E9TOOL_OBJS)
+	$(CXX) $(CXXFLAGS) $(E9TOOL_OBJS) -o e9tool libZydis.a \
+        -Wl,--dynamic-list=src/e9tool/e9tool.syms -ldl
+
+tool.sanitize: CXXFLAGS += -O0 -g -I src/e9tool/ -I zydis/include/ \
     -I zydis/dependencies/zycore/include/ -Wno-unused-function \
     -fsanitize=address
-tool.debug: $(E9TOOL_OBJS)
+tool.sanitize: $(E9TOOL_OBJS)
 	$(CXX) $(CXXFLAGS) $(E9TOOL_OBJS) -o e9tool libZydis.a \
         -Wl,--dynamic-list=src/e9tool/e9tool.syms -ldl
 
diff --git a/src/e9patch/e9x86_64.cpp b/src/e9patch/e9x86_64.cpp
@@ -392,7 +392,8 @@ int relocateInstr(intptr_t addr, int32_t offset32, const uint8_t *bytes,
 
                     // Normal case:
                     buf->push(modRM);
-                    if (mod == 0x0 && rm == 0x05)
+                    if (mod == 0x0 && rm == 0x05 &&
+                            size - i - 1 >= sizeof(uint32_t))
                     {
                         // This is a %rip-relative call, so we must adjust 
                         int32_t pcrel32 = *(uint32_t *)(bytes + i + 1);
@@ -591,7 +592,7 @@ int relocateInstr(intptr_t addr, int32_t offset32, const uint8_t *bytes,
     uint32_t modRM = bytes[i++];
     uint8_t mod = (modRM & 0xc0) >> 6;
     uint8_t rm  = modRM & 0x7;
-    if (mod == 0x0 && rm == 0x05)
+    if (mod == 0x0 && rm == 0x05 && size - i >= sizeof(uint32_t))
     {
         // i points to a %rip-relative displacement.  We adjust accordingly.
         int32_t pcrel32 = *(uint32_t *)(bytes + i);
