| Date | Wed, 29 Dec 2021 12:17:30 +0100 | From | Pavel Machek <> | Subject | Re: [PATCH 5.10 26/76] sfc: Check null pointer of rx_queue->page_ring |
| |
hi!
> From: Jiasheng Jiang <jiasheng@iscas.ac.cn> > > [ 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 -- DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany [unhandled content-type:application/pgp-signature] |