From bd6682a61d3f03d8656429c6875fba3fdea8b1ad Mon Sep 17 00:00:00 2001
From: mykola2312 <49044616+mykola2312@users.noreply.github.com>
Date: Mon, 19 Aug 2024 08:48:30 +0300
Subject: [PATCH] fix bug when 1-byte opcode will trigger size-limit because of
 unnecessary bounds check

---
 src/rtdisasm.c           | 8 ++++++--
 src/rtdisasm_test.c      | 5 +++--
 src/rtdisasm_test_data.s | 1 +
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/rtdisasm.c b/src/rtdisasm.c
index 227adad..d939a47 100644
--- a/src/rtdisasm.c
+++ b/src/rtdisasm.c
@@ -312,11 +312,15 @@ int rtdisasm_analyze_single(const uint8_t* code, unsigned size, const instructio
     if (type == INSTRUCTION_STD)
     {
         if (ins->config.has_imm)
+        {
             cur += imm2length(ins->std.imm);
+            if (cur >= end) return -1;
+        }
         else if (ins->config.has_value)
+        {
             cur += value2length(ins->std.value);
-        
-        if (cur >= end) return -1;
+            if (cur >= end) return -1;
+        }
     }
 
     // set found
diff --git a/src/rtdisasm_test.c b/src/rtdisasm_test.c
index e8d4c92..70ff15e 100644
--- a/src/rtdisasm_test.c
+++ b/src/rtdisasm_test.c
@@ -7,8 +7,9 @@ extern void test_1_end();
 int main()
 {
     size_t size = (uintptr_t)test_1_end - (uintptr_t)test_1;
-    int len = rtdisasm_analyze_single((const uint8_t*)test_1, size, NULL);
-    printf("rtdisasm_analyze_single: len %d\n", len);
+    printf("size %lu\n", size);
+    // int len = rtdisasm_analyze_single((const uint8_t*)test_1, size, NULL);
+    // printf("rtdisasm_analyze_single: len %d\n", len);
 
     int offset = rtdisasm_find_target((const uint8_t*)test_1, size, RT_TARGET_NOP);
     printf("rtdisasm_find_target: offset %d\n", offset);
diff --git a/src/rtdisasm_test_data.s b/src/rtdisasm_test_data.s
index 46d8fd2..c2368c8 100644
--- a/src/rtdisasm_test_data.s
+++ b/src/rtdisasm_test_data.s
@@ -3,6 +3,7 @@
 .globl test_1_end
 
 test_1:
+    push %rax
     push (%rbp)
 
     nop # target that rtdisasm must reach