Re: [PATCH net v2] mctp i2c: handle NULL header address

[kernel test robot]

Hi Matt,

kernel test robot noticed the following build warnings:

[auto build test WARNING on cb560795c8c2ceca1d36a95f0d1b2eafc4074e37]

url:    https://github.com/intel-lab-lkp/linux/commits/Matt-Johnston/mctp-i2c-handle-NULL-header-address/20241021-123741
base:   cb560795c8c2ceca1d36a95f0d1b2eafc4074e37
patch link:    https://lore.kernel.org/r/20241021-mctp-i2c-null-dest-v2-1-4503e478517c%40codeconstruct.com.au
patch subject: [PATCH net v2] mctp i2c: handle NULL header address
config: alpha-randconfig-r122-20241022 (https://download.01.org/0day-ci/archive/20241022/202410221734.IWc5paM1-lkp@xxxxxxxxx/config)
compiler: alpha-linux-gcc (GCC) 13.3.0
reproduce: (https://download.01.org/0day-ci/archive/20241022/202410221734.IWc5paM1-lkp@xxxxxxxxx/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202410221734.IWc5paM1-lkp@xxxxxxxxx/

sparse warnings: (new ones prefixed by >>)
>> drivers/net/mctp/mctp-i2c.c:599:23: sparse: sparse: incorrect type in assignment (different base types) @@     expected unsigned char [assigned] [usertype] llsrc @@     got unsigned char const *dev_addr @@
   drivers/net/mctp/mctp-i2c.c:599:23: sparse:     expected unsigned char [assigned] [usertype] llsrc
   drivers/net/mctp/mctp-i2c.c:599:23: sparse:     got unsigned char const *dev_addr
   drivers/net/mctp/mctp-i2c.c: note: in included file (through include/linux/module.h):
   include/linux/list.h:83:21: sparse: sparse: self-comparison always evaluates to true
   include/linux/list.h:83:21: sparse: sparse: self-comparison always evaluates to true

vim +599 drivers/net/mctp/mctp-i2c.c

   579	
   580	static int mctp_i2c_header_create(struct sk_buff *skb, struct net_device *dev,
   581					  unsigned short type, const void *daddr,
   582					  const void *saddr, unsigned int len)
   583	{
   584		struct mctp_i2c_hdr *hdr;
   585		struct mctp_hdr *mhdr;
   586		u8 lldst, llsrc;
   587	
   588		if (len > MCTP_I2C_MAXMTU)
   589			return -EMSGSIZE;
   590	
   591		if (daddr)
   592			lldst = *((u8 *)daddr);
   593		else
   594			return -EINVAL;
   595	
   596		if (saddr)
   597			llsrc = *((u8 *)saddr);
   598		else
 > 599			llsrc = dev->dev_addr;
   600	
   601		skb_push(skb, sizeof(struct mctp_i2c_hdr));
   602		skb_reset_mac_header(skb);
   603		hdr = (void *)skb_mac_header(skb);
   604		mhdr = mctp_hdr(skb);
   605		hdr->dest_slave = (lldst << 1) & 0xff;
   606		hdr->command = MCTP_I2C_COMMANDCODE;
   607		hdr->byte_count = len + 1;
   608		hdr->source_slave = ((llsrc << 1) & 0xff) | 0x01;
   609		mhdr->ver = 0x01;
   610	
   611		return sizeof(struct mctp_i2c_hdr);
   612	}
   613	

-- 
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https://github.com/intel/lkp-tests/wiki