Re: [PATCH v3] staging: pi433: fix race condition in pi433_ioctl

[kbuild test robot]

Hi Hugo,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on staging/staging-testing]
[also build test ERROR on v4.17 next-20180613]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Hugo-Lefeuvre/staging-pi433-fix-race-condition-in-pi433_ioctl/20180614-091011
config: i386-randconfig-s0-201823 (attached as .config)
compiler: gcc-6 (Debian 6.4.0-9) 6.4.0 20171026
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

All errors (new ones prefixed by >>):

   In file included from arch/x86/include/asm/string.h:3:0,
                    from include/linux/string.h:20,
                    from arch/x86/include/asm/page_32.h:35,
                    from arch/x86/include/asm/page.h:14,
                    from arch/x86/include/asm/thread_info.h:12,
                    from include/linux/thread_info.h:38,
                    from arch/x86/include/asm/preempt.h:7,
                    from include/linux/preempt.h:81,
                    from include/linux/spinlock.h:51,
                    from include/linux/seqlock.h:36,
                    from include/linux/time.h:6,
                    from include/linux/stat.h:19,
                    from include/linux/module.h:10,
                    from drivers/staging//pi433/pi433_if.c:31:
   drivers/staging//pi433/pi433_if.c: In function 'pi433_ioctl':
>> drivers/staging//pi433/pi433_if.c:909:30: error: 'tx_cfg_buffer' undeclared (first use in this function)
      memcpy(&instance->tx_cfg, &tx_cfg_buffer, sizeof(struct pi433_tx_cfg));
                                 ^
   arch/x86/include/asm/string_32.h:183:45: note: in definition of macro 'memcpy'
    #define memcpy(t, f, n) __builtin_memcpy(t, f, n)
                                                ^
   drivers/staging//pi433/pi433_if.c:909:30: note: each undeclared identifier is reported only once for each function it appears in
      memcpy(&instance->tx_cfg, &tx_cfg_buffer, sizeof(struct pi433_tx_cfg));
                                 ^
   arch/x86/include/asm/string_32.h:183:45: note: in definition of macro 'memcpy'
    #define memcpy(t, f, n) __builtin_memcpy(t, f, n)
                                                ^

vim +/tx_cfg_buffer +909 drivers/staging//pi433/pi433_if.c

   876	
   877	static long
   878	pi433_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
   879	{
   880		int			retval = 0;
   881		struct pi433_instance	*instance;
   882		struct pi433_device	*device;
   883		struct pi433_tx_cfg	tx_cfg;
   884		void __user *argp = (void __user *)arg;
   885	
   886		/* Check type and command number */
   887		if (_IOC_TYPE(cmd) != PI433_IOC_MAGIC)
   888			return -ENOTTY;
   889	
   890		/* TODO? guard against device removal before, or while,
   891		 * we issue this ioctl. --> device_get()
   892		 */
   893		instance = filp->private_data;
   894		device = instance->device;
   895	
   896		if (!device)
   897			return -ESHUTDOWN;
   898	
   899		switch (cmd) {
   900		case PI433_IOC_RD_TX_CFG:
   901			if (copy_to_user(argp, &instance->tx_cfg,
   902					 sizeof(struct pi433_tx_cfg)))
   903				return -EFAULT;
   904			break;
   905		case PI433_IOC_WR_TX_CFG:
   906			if (copy_from_user(&tx_cfg, argp, sizeof(struct pi433_tx_cfg)))
   907				return -EFAULT;
   908			mutex_lock(&device->tx_fifo_lock);
 > 909			memcpy(&instance->tx_cfg, &tx_cfg_buffer, sizeof(struct pi433_tx_cfg));
   910			mutex_unlock(&device->tx_fifo_lock);
   911			break;
   912		case PI433_IOC_RD_RX_CFG:
   913			if (copy_to_user(argp, &device->rx_cfg,
   914					 sizeof(struct pi433_rx_cfg)))
   915				return -EFAULT;
   916			break;
   917		case PI433_IOC_WR_RX_CFG:
   918			mutex_lock(&device->rx_lock);
   919	
   920			/* during pendig read request, change of config not allowed */
   921			if (device->rx_active) {
   922				mutex_unlock(&device->rx_lock);
   923				return -EAGAIN;
   924			}
   925	
   926			if (copy_from_user(&device->rx_cfg, argp,
   927					   sizeof(struct pi433_rx_cfg))) {
   928				mutex_unlock(&device->rx_lock);
   929				return -EFAULT;
   930			}
   931	
   932			mutex_unlock(&device->rx_lock);
   933			break;
   934		default:
   935			retval = -EINVAL;
   936		}
   937	
   938		return retval;
   939	}
   940	

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