Re: [dpdk-dev] [PATCH] net/igc: fix memory illegal accesses

["Zhang, AlvinX" <alvinx.zhang@intel.com>]

Hi Jia,
First of all, this is a coverity issue, and it's really a false positives. But do some macro checking will improve code robustness.

Thanks,
Alvin

> -----Original Message-----
> From: Guo, Jia
> Sent: Thursday, May 7, 2020 2:30 PM
> To: Zhang, AlvinX <alvinx.zhang@intel.com>; dev@dpdk.org
> Cc: Zhao1, Wei <wei.zhao1@intel.com>; Ye, Xiaolong
> <xiaolong.ye@intel.com>
> Subject: Re: [PATCH] net/igc: fix memory illegal accesses
> 
> hi, alvin
> 
> 
> On 5/7/2020 10:01 AM, alvinx.zhang@intel.com wrote:
> > From: Alvin Zhang <alvinx.zhang@intel.com>
> >
> > Add memory access out-of-bounds check.
> 
> 
> Could you explain why add ...?  If not add, what issue?
> 
> 
> >
> > Fixes: bd3fcf0d0fa1 (net/igc: support RSS)
> > Cc: stable@dpdk.org
> >
> > Signed-off-by: Alvin Zhang <alvinx.zhang@intel.com>
> > ---
> >   drivers/net/igc/igc_ethdev.c | 12 ++++++++++--
> >   1 file changed, 10 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/igc/igc_ethdev.c
> > b/drivers/net/igc/igc_ethdev.c index 16d98c6..ced8ffd 100644
> > --- a/drivers/net/igc/igc_ethdev.c
> > +++ b/drivers/net/igc/igc_ethdev.c
> > @@ -2266,6 +2266,8 @@ static int eth_igc_vlan_tpid_set(struct
> rte_eth_dev *dev,
> >   		return -EINVAL;
> >   	}
> >
> > +	RTE_BUILD_BUG_ON(ETH_RSS_RETA_SIZE_128 %
> IGC_RSS_RDT_REG_SIZE);
> > +
> >   	/* set redirection table */
> >   	for (i = 0; i < ETH_RSS_RETA_SIZE_128; i += IGC_RSS_RDT_REG_SIZE)
> {
> >   		union igc_rss_reta_reg reta, reg;
> > @@ -2278,7 +2280,8 @@ static int eth_igc_vlan_tpid_set(struct
> rte_eth_dev *dev,
> >   				IGC_RSS_RDT_REG_SIZE_MASK);
> >
> >   		/* if no need to update the register */
> > -		if (!mask)
> > +		if (!mask ||
> > +			shift > (RTE_RETA_GROUP_SIZE -
> IGC_RSS_RDT_REG_SIZE))
> 
> 
> alignment should be match above parentheses.
> 
> 
> >   			continue;
> >
> >   		/* check mask whether need to read the register value first
> */ @@
> > -2289,6 +2292,7 @@ static int eth_igc_vlan_tpid_set(struct rte_eth_dev
> *dev,
> >   					IGC_RETA(i /
> IGC_RSS_RDT_REG_SIZE));
> >
> >   		/* update the register */
> > +		RTE_BUILD_BUG_ON(sizeof(reta.bytes) !=
> IGC_RSS_RDT_REG_SIZE);
> >   		for (j = 0; j < IGC_RSS_RDT_REG_SIZE; j++) {
> >   			if (mask & (1u << j))
> >   				reta.bytes[j] =
> > @@ -2318,6 +2322,8 @@ static int eth_igc_vlan_tpid_set(struct
> rte_eth_dev *dev,
> >   		return -EINVAL;
> >   	}
> >
> > +	RTE_BUILD_BUG_ON(ETH_RSS_RETA_SIZE_128 %
> IGC_RSS_RDT_REG_SIZE);
> > +
> >   	/* read redirection table */
> >   	for (i = 0; i < ETH_RSS_RETA_SIZE_128; i += IGC_RSS_RDT_REG_SIZE)
> {
> >   		union igc_rss_reta_reg reta;
> > @@ -2330,12 +2336,14 @@ static int eth_igc_vlan_tpid_set(struct
> rte_eth_dev *dev,
> >   				IGC_RSS_RDT_REG_SIZE_MASK);
> >
> >   		/* if no need to read register */
> > -		if (!mask)
> > +		if (!mask ||
> > +			shift > (RTE_RETA_GROUP_SIZE -
> IGC_RSS_RDT_REG_SIZE))
> 
> 
> the same as above.
> 
> 
> >   			continue;
> >
> >   		/* read register and get the queue index */
> >   		reta.dword = IGC_READ_REG_LE_VALUE(hw,
> >   				IGC_RETA(i / IGC_RSS_RDT_REG_SIZE));
> > +		RTE_BUILD_BUG_ON(sizeof(reta.bytes) !=
> IGC_RSS_RDT_REG_SIZE);
> 
> 
> need null line or no need, please check it at the place and before.
> 
> 
> >   		for (j = 0; j < IGC_RSS_RDT_REG_SIZE; j++) {
> >   			if (mask & (1u << j))
> >   				reta_conf[idx].reta[shift + j] = reta.bytes[j];