Re: [PATCH v2] mm/hmm/test: use after free in dmirror_allocate_chunk()

[Ralph Campbell]

On 9/24/20 6:46 AM, Dan Carpenter wrote:
> The error handling code does this:
>
> err_free:
> 	kfree(devmem);
>          ^^^^^^^^^^^^^
> err_release:
> 	release_mem_region(devmem->pagemap.range.start, range_len(&devmem->pagemap.range));
>                             ^^^^^^^^
> The problem is that when we use "devmem->pagemap.range.start" the
> "devmem" pointer is either NULL or freed.
>
> Neither the allocation nor the call to request_free_mem_region() has to
> be done under the lock so I moved those to the start of the function.
>
> Fixes: b2ef9f5a5cb3 ("mm/hmm/test: add selftest driver for HMM")
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

Looks good.
Reviewed-by: Ralph Campbell <rcampbell@xxxxxxxxxx>