Re: [Qemu-devel] [PATCH] migration: fix potential overflow in multifd send

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Peter Xu (peterx@redhat.com) wrote:
> I would guess it won't happen normally, but this should ease Coverity.
> 
> >>>     CID 1394385:  Integer handling issues  (OVERFLOW_BEFORE_WIDEN)
> >>>     Potentially overflowing expression "pages->used * 8192U" with type "unsigned int" (32 bits, unsigned) is evaluated using 32-bit arithmetic, and then used in a context that expects an expression of type "uint64_t" (64 bits, unsigned).
> 854         transferred = pages->used * TARGET_PAGE_SIZE + p->packet_len;
> 
> Fixes: CID 1394385
> CC: Juan Quintela <quintela@redhat.com>
> Signed-off-by: Peter Xu <peterx@redhat.com>

Queued

> ---
>  migration/ram.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/migration/ram.c b/migration/ram.c
> index 52dd678092..fdd108475c 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -851,7 +851,7 @@ static void multifd_send_pages(void)
>      p->pages->block = NULL;
>      multifd_send_state->pages = p->pages;
>      p->pages = pages;
> -    transferred = pages->used * TARGET_PAGE_SIZE + p->packet_len;
> +    transferred = ((uint64_t) pages->used) * TARGET_PAGE_SIZE + p->packet_len;
>      ram_counters.multifd_bytes += transferred;
>      ram_counters.transferred += transferred;;
>      qemu_mutex_unlock(&p->mutex);
> -- 
> 2.17.1
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK