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SubjectRe: [PATCH 4.19 19/38] sfc: falcon: Check null pointer of rx_queue->page_ring
Hi!

> From: Jiasheng Jiang <jiasheng@iscas.ac.cn>
>
> [ Upstream commit 9b8bdd1eb5890aeeab7391dddcf8bd51f7b07216 ]
>
> Because of the possible failure of the kcalloc, it should be better to
> set rx_queue->page_ptr_mask to 0 when it happens in order to maintain
> the consistency.

Again this is confusing/wrong, or at least not a complete fix...

> +++ b/drivers/net/ethernet/sfc/falcon/rx.c
> @@ -732,7 +732,10 @@ static void ef4_init_rx_recycle_ring(struct ef4_nic *efx,
> efx->rx_bufs_per_page);
> rx_queue->page_ring = kcalloc(page_ring_size,
> sizeof(*rx_queue->page_ring), GFP_KERNEL);
> - rx_queue->page_ptr_mask = page_ring_size - 1;
> + if (!rx_queue->page_ring)
> + rx_queue->page_ptr_mask = 0;
> + else
> + rx_queue->page_ptr_mask = page_ring_size - 1;
> }
>

...as we have

index = rx_queue->page_remove & rx_queue->page_ptr_mask;
page = rx_queue->page_ring[index];

in ef4_reuse_page, and similar problems in other places, including

for (i = 0; i <= rx_queue->page_ptr_mask; i++) {
struct page *page = rx_queue->page_ring[i];

. Best regards,
Pavel
--
DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
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