RE: [Intel-wired-lan] [PATCH v2] e1000e: Modify tx/rx configurations to avoid null pointer dereferences in e1000_open

[Brown, Aaron F]

> From: Intel-wired-lan [mailto:intel-wired-lan-bounces@xxxxxxxxxxxxxxxx] On
> Behalf Of Jia-Ju Bai
> Sent: Wednesday, August 05, 2015 3:16 AM
> To: Kirsher, Jeffrey T; Brandeburg, Jesse
> Cc: netdev@xxxxxxxxxxxxxxx; Jia-Ju Bai; intel-wired-lan@xxxxxxxxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx
> Subject: [Intel-wired-lan] [PATCH v2] e1000e: Modify tx/rx configurations
> to avoid null pointer dereferences in e1000_open
> 
> When e1000e_setup_rx_resources is failed in e1000_open,
> e1000e_free_tx_resources in "err_setup_rx" segment is executed.
> "writel(0, tx_ring->head)" statement in e1000_clean_tx_ring
> in e1000e_free_tx_resources will cause a null poonter dereference(crash),
> because "tx_ring->head" is only assigned in e1000_configure_tx
> in e1000_configure, but it is after e1000e_setup_rx_resources.
> 
> This patch moves head/tail register writing to e1000_configure_tx/rx,
> which can fix this problem. It is inspired by igb_configure_tx_ring
> in the igb driver.
> 
> Specially, thank Alexander Duyck for his valuable suggestion.
> 
> Signed-off-by: Jia-Ju Bai <baijiaju1990@xxxxxxx>
> ---
>  drivers/net/ethernet/intel/e1000e/netdev.c |   24 ++++++++++++-----------
> -
>  1 file changed, 12 insertions(+), 12 deletions(-)

Tested-by: Aaron Brown <aaron.f.brown@xxxxxxxxx>
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