[Devel] [PATCH rh7 v2] ploop: Fix the check that nobody writes to ZERO_PAGE()

[Kirill Tkhai]

On 27.08.2019 12:38, Konstantin Khorenko wrote:
> The check must verify the destination page, not the source one.
> 
> Fixes: 3a44b99ce15e ("ploop: Check that nobody writes to ZERO_PAGE()")
> https://jira.sw.ru/browse/PSBM-97043
> 
> Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>

Reviewed-by: Kirill Tkhai <ktkhai at virtuozzo.com>

> 
> --
> v2: move the check in bcopy_from_blist() out of the cycle
> ---
>  drivers/block/ploop/dev.c       | 2 +-
>  drivers/block/ploop/io_direct.c | 3 ++-
>  2 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/block/ploop/dev.c b/drivers/block/ploop/dev.c
> index 6fb95f0fadb6..b6cb408347d2 100644
> --- a/drivers/block/ploop/dev.c
> +++ b/drivers/block/ploop/dev.c
> @@ -1583,7 +1583,7 @@ static void bio_bcopy(struct bio *dst, struct bio *src, struct ploop_device *plo
>  		if (copy > PAGE_SIZE - poff)
>  			copy = PAGE_SIZE - poff;
>  
> -		WARN_ON_ONCE(bv->bv_page == ZERO_PAGE(0));
> +		WARN_ON_ONCE(dst->bi_io_vec[didx].bv_page == ZERO_PAGE(0));
>  		ksrc = kmap_atomic(bv->bv_page);
>  		memcpy(page_address(dst->bi_io_vec[didx].bv_page) + poff,
>  		       ksrc + bv->bv_offset + bv_off,
> diff --git a/drivers/block/ploop/io_direct.c b/drivers/block/ploop/io_direct.c
> index 6b4fd667ff71..1beb4f3292a2 100644
> --- a/drivers/block/ploop/io_direct.c
> +++ b/drivers/block/ploop/io_direct.c
> @@ -344,11 +344,12 @@ static void bcopy_from_blist(struct page *page, int dst_off, /* dst */
>  {
>  	u8 *kdst = kmap_atomic(page);
>  
> +	WARN_ON_ONCE(page == ZERO_PAGE(0));
> +
>  	while (copy_len > 0) {
>  		u8 *ksrc;
>  		int copy = MIN(copy_len, biter->bv->bv_len - biter->off);
>  
> -		WARN_ON_ONCE(biter->bv->bv_page == ZERO_PAGE(0));
>  		ksrc = kmap_atomic(biter->bv->bv_page);
>  		memcpy(kdst + dst_off,
>  		       ksrc + biter->bv->bv_offset + biter->off,
>