Re: [PATCH 2/2] xen/gunzip: Allow perform_gunzip() to be called multiple times

[Jan Beulich <jbeulich@xxxxxxxx>]

On 02.04.2021 17:21, Julien Grall wrote:
> From: Julien Grall <jgrall@xxxxxxxxxx>
> 
> Currently perform_gunzip() can only be called once because the
> the internal state (e.g allocate) is not fully re-initialized.
> 
> This works fine if you are only booting dom0. But this will break when
> booting multiple using the dom0less that uses compressed kernel images.
> 
> This can be resolved by re-initializing bytes_out, malloc_ptr,
> malloc_count every time perform_gunzip() is called.
> 
> Note the latter is only re-initialized for hardening purpose as there is
> no guarantee that every malloc() are followed by free() (It should in
> theory!).
> 
> Take the opportunity to check the return of alloc_heap_pages() to return
> an error rather than dereferencing a NULL pointer later on failure.
> 
> Reported-by: Charles Chiou <cchiou@xxxxxxxxxxxxx>
> Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>