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From: "Philippe Mathieu-Daudé" <philmd@redhat.com>
To: Peter Maydell <peter.maydell@linaro.org>, qemu-devel@nongnu.org
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>,
	Juan Quintela <quintela@redhat.com>
Subject: Re: [Qemu-devel] [PATCH for-4.0] migration/ram.c: Fix use-after-free in multifd_recv_unfill_packet()
Date: Tue, 9 Apr 2019 20:49:48 +0200	[thread overview]
Message-ID: <585e8815-9c3c-d532-c32b-02bab712c315@redhat.com> (raw)
In-Reply-To: <20190409151830.6024-1-peter.maydell@linaro.org>

On 4/9/19 5:18 PM, Peter Maydell wrote:
> Coverity points out (CID 1400442) that in this code:
> 
>     if (packet->pages_alloc > p->pages->allocated) {
>         multifd_pages_clear(p->pages);
>         multifd_pages_init(packet->pages_alloc);
>     }
> 
> we free p->pages in multifd_pages_clear() but continue to
> use it in the following code. We also leak memory, because
> multifd_pages_init() returns the pointer to a new MultiFDPages_t
> struct but we are ignoring its return value.
> 
> Fix both of these bugs by adding the missing assignment of
> the newly created struct to p->pages.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

> ---
> I don't know anything about the multifd code, but this seems like
> the obvious fix based on looking at what the clear and init
> functions are doing. I have only run 'make check' on this,
> so review and testing definitely in order. I think we should
> really put this into 4.0, which means ideally I'd like to
> commit it to master today or tomorrow, though...
> ---
>  migration/ram.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/migration/ram.c b/migration/ram.c
> index f68beeeeffc..1ca9ba77b6a 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -851,7 +851,7 @@ static int multifd_recv_unfill_packet(MultiFDRecvParams *p, Error **errp)
>       */
>      if (packet->pages_alloc > p->pages->allocated) {
>          multifd_pages_clear(p->pages);
> -        multifd_pages_init(packet->pages_alloc);
> +        p->pages = multifd_pages_init(packet->pages_alloc);
>      }
>  
>      p->pages->used = be32_to_cpu(packet->pages_used);
> 

  parent reply	other threads:[~2019-04-09 18:50 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-09 15:18 [Qemu-devel] [PATCH for-4.0] migration/ram.c: Fix use-after-free in multifd_recv_unfill_packet() Peter Maydell
2019-04-09 15:18 ` Peter Maydell
2019-04-09 15:46 ` Juan Quintela
2019-04-09 15:46   ` Juan Quintela
2019-04-09 19:47   ` Peter Maydell
2019-04-09 19:47     ` Peter Maydell
2019-04-09 18:49 ` Philippe Mathieu-Daudé [this message]
2019-04-09 18:49   ` Philippe Mathieu-Daudé

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