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Re: [Qemu-devel] [PATCH] Fix off-by-1 error in RAM migration code
From: |
Orit Wasserman |
Subject: |
Re: [Qemu-devel] [PATCH] Fix off-by-1 error in RAM migration code |
Date: |
Wed, 31 Oct 2012 13:08:16 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20121016 Thunderbird/16.0.1 |
On 10/31/2012 05:43 AM, David Gibson wrote:
> The code for migrating (or savevm-ing) memory pages starts off by creating
> a dirty bitmap and filling it with 1s. Except, actually, because bit
> addresses are 0-based it fills every bit except bit 0 with 1s and puts an
> extra 1 beyond the end of the bitmap, potentially corrupting unrelated
> memory. Oops. This patch fixes it.
>
> Signed-off-by: David Gibson <address@hidden>
> ---
> arch_init.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch_init.c b/arch_init.c
> index e6effe8..b75a4c5 100644
> --- a/arch_init.c
> +++ b/arch_init.c
> @@ -568,7 +568,7 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
> int64_t ram_pages = last_ram_offset() >> TARGET_PAGE_BITS;
>
> migration_bitmap = bitmap_new(ram_pages);
> - bitmap_set(migration_bitmap, 1, ram_pages);
> + bitmap_set(migration_bitmap, 0, ram_pages);
> migration_dirty_pages = ram_pages;
>
> bytes_transferred = 0;
>
You are correct, good catch.
Reviewed-by: Orit Wasserman <address@hidden>