hi!
> From: Jiasheng Jiang <jiasheng@xxxxxxxxxxx>
>
> [ Upstream commit bdf1b5c3884f6a0dc91b0dbdb8c3b7d205f449e0 ]
>
> 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.
This is confusing/wrong, or at least not a complete fix.
> +++ b/drivers/net/ethernet/sfc/rx_common.c
> @@ -150,7 +150,10 @@ static void efx_init_rx_recycle_ring(struct efx_rx_queue *rx_queue)
> 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;
> }
>
So we have !rx_queue->page_ring. But in efx_reuse_page, we do
index = rx_queue->page_remove & rx_queue->page_ptr_mask;
page = rx_queue->page_ring[index];
So index is now zero, but we'll derefernce null pointer anyway.
Best regards,
Pavel
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