leave trashes esp

[jimg]

I've been searching for a bug all day that causes masm 6.14 and 6.15 to crash, but no uasm.

Here's a little prog that shows the problem

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include \masm32\include\masm32rt.inc

.code
PutString proc locx
   pusha
   mov esi,locx
   .repeat
      lodsb
      or al,al
      .break .if zero?
      invoke crt__fputchar,al
   .until 0
   popa
ret
PutString endp

.data
testx db "test",0
.code
program:
nop
   invoke PutString,addr testx
nop
inkey "exit?"
invoke ExitProcess,0   
end program


Tracing in Olly, I find that the leave at the end of the proc trashes esp, so the proc returns to some random spot and crashes.

I vaguely seem to recall something nasty about leave in the past, but I've never had masm crash like this before.  Is there something in this code that causes the problem?

[jj2007]

Leave is innocent:

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mlv615
enter repeat    x:esp           0018FF60
test
exit repeat     x:esp           0018FF58

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UAsm64
enter repeat    x:esp           0018FF60
test
exit repeat     x:esp           0018FF60

Remember that leave depends on ebp, and that you are using pushad+popad. Masm handles invoke crt__fputchar,al differently - call it a bug.