Re: [PATCH] mremap NULL pointer dereference fix

[Linus Torvalds]

On Mon, 16 Feb 2004, Andrew Morton wrote:
> 
> This saves a goto.   It works, but I wasn't able to trigger
> the oops without it either.

To trigger the bug you have to have _just_ the right memory usage, I 
suspect. You literally have to have the destination page directory 
allocation unmap the _exact_ source page (which has to be clean) for the 
bug to hit. 

So I suspect the oops only triggers on the machine that the trigger
program was written for.

Your version of the patch saves a goto in the source, but results in an 
extra goto in the generated assembly unless the compiler is clever enough 
to notice the double test for NULL.

Never mind, that's a micro-optimization, and your version is cleaner. 
Let's go with it if Rajesh can verify that it fixes the problem for him.

Rajesh?

		Linus
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