Re: [dpdk-dev] [dpdk-stable] [PATCH] net/axgbe: fix double unlock coverity issue

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 9/19/2019 12:01 PM, Pallantla Poornima wrote:
> One issue caught by Coverity 340835
> *unlock: axgbe_phy_set_mode unlocks pdata->phy_mutex
> *double_unlock: axgbe_phy_sfp_detect unlocks pdata->phy_mutex
> while it is unlocked.
> 
> In axgbe_phy_sfp_detect()/axgbe_phy_set_redrv_mode(),
> axgbe_phy_get_comm_ownership() and axgbe_phy_put_comm_ownership()
> are invoked subsequently.
> 
> Currently in axgbe_phy_get_comm_ownership(), during one of the case
> 'phy_data->comm_owned' is not protected and before returning 0,
> lock is not called and unlock is called in axgbe_phy_put_comm_ownership()
> directly which is incorrect.
> 
> Ideally, the variable 'phy_data->comm_owned' needs to be protected.
> During success scenario, lock is called in axgbe_phy_get_comm_ownership()
> followed by unlock in axgbe_phy_put_comm_ownership().
> In failure case, unlock is invoked in axgbe_phy_get_comm_ownership()
> itself appropriately.
> 
> The fix is to protect 'phy_data->comm_owned' in the identified case
> ensuring locks/unlocks properly exist.
> 
> Coverity issue: 340835
> Fixes: a5c7273771 ("net/axgbe: add phy programming APIs")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Pallantla Poornima <pallantlax.poornima@intel.com>

lgtm, 'axgbe_phy_put_comm_ownership()' expects 'axgbe_phy_get_comm_ownership()'
gets the lock. Thanks for fixing the coverity issue.

But still, Ravi can you please review/test the patch?

Thanks,
ferruh

> ---
>  drivers/net/axgbe/axgbe_phy_impl.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/axgbe/axgbe_phy_impl.c b/drivers/net/axgbe/axgbe_phy_impl.c
> index 973177f69..2267c5f81 100644
> --- a/drivers/net/axgbe/axgbe_phy_impl.c
> +++ b/drivers/net/axgbe/axgbe_phy_impl.c
> @@ -412,15 +412,15 @@ static int axgbe_phy_get_comm_ownership(struct axgbe_port *pdata)
>  	uint64_t timeout;
>  	unsigned int mutex_id;
>  
> -	if (phy_data->comm_owned)
> -		return 0;
> -
>  	/* The I2C and MDIO/GPIO bus is multiplexed between multiple devices,
>  	 * the driver needs to take the software mutex and then the hardware
>  	 * mutexes before being able to use the busses.
>  	 */
>  	pthread_mutex_lock(&pdata->phy_mutex);
>  
> +	if (phy_data->comm_owned)
> +		return 0;
> +
>  	/* Clear the mutexes */
>  	XP_IOWRITE(pdata, XP_I2C_MUTEX, AXGBE_MUTEX_RELEASE);
>  	XP_IOWRITE(pdata, XP_MDIO_MUTEX, AXGBE_MUTEX_RELEASE);
>