使用ASM修改字符数组触发Access Violation，能否绕过该错误？

Absolutely—you can work around this access violation, but first we need to nail down why it’s happening. 9 times out of 10, this error pops up because the character array you’re trying to modify lives in a read-only memory segment (like the .text section, where compilers often store string constants, or a memory page marked as read-only by the OS).

Here’s how to fix it, step by step:

1. Verify the Memory Segment’s Permissions #

First, confirm the issue in OllyDbg:

• Right-click the problematic address [ADDR] in the CPU window.
• Hover over Memory → Open Memory Window.
• Look at the "Access" column for that memory page. If it says R (read-only) instead of RW (read-write), that’s your culprit.

2. Modify Memory Permissions Temporarily (Debugging Only) #

If you just need to patch it for debugging, OllyDbg lets you tweak memory access directly:

• In the Memory Window, right-click the target page.
• Select Set memory access → Check the Write box and click OK.
• Now you can run your ASM write instruction without the access violation.

3. Permanently Fix It via ASM Code #

If you want your patch to work outside the debugger, use the Windows VirtualProtect API to change permissions at runtime. Add this code before your write operation:

; Set [ADDR]'s memory page to read-write
push PAGE_READWRITE   ; New protection flag (0x4)
push 0x1000           ; Size of the memory page (adjust if needed)
push [ADDR]           ; Starting address of the target memory
call VirtualProtect   ; Windows API to modify memory protection

After modifying the character, you can even reset the permissions back to read-only if you want to maintain security.

4. Alternative: Move the Character Array to a Writable Segment #

If you control the original code (not just patching a binary), move the character array to a writable section like .data or .bss instead of leaving it in .text. For example:

; Instead of putting the string in .text (read-only)
section .text
db "Hello World", 0

; Move it to .data (read-write)
section .data
my_string db "Hello World", 0

A Quick Heads-Up #

• Be cautious with modifying memory permissions in production code—it can introduce security vulnerabilities if not handled properly.
• If you’re patching a program with anti-debugging or memory protection (like DEP), you might need additional steps to bypass those safeguards, but this basic workflow covers most common cases.

内容的提问来源于stack exchange，提问作者Hi_World