Re: [PATCH v3] cdx: Fix possible UAF error in driver_override_show()

[kernel test robot <lkp@intel.com>]

Hi Qiu-ji,

kernel test robot noticed the following build warnings:

[auto build test WARNING on linus/master]
[also build test WARNING on v6.13-rc7 next-20250117]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Qiu-ji-Chen/cdx-Fix-possible-UAF-error-in-driver_override_show/20250115-170808
base:   linus/master
patch link:    https://lore.kernel.org/r/20250115090449.102060-1-chenqiuji666%40gmail.com
patch subject: [PATCH v3] cdx: Fix possible UAF error in driver_override_show()
config: arm64-randconfig-004-20250116 (https://download.01.org/0day-ci/archive/20250118/202501180719.sDmtGnhD-lkp@intel.com/config)
compiler: clang version 20.0.0git (https://github.com/llvm/llvm-project f5cd181ffbb7cb61d582fe130d46580d5969d47a)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250118/202501180719.sDmtGnhD-lkp@intel.com/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@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202501180719.sDmtGnhD-lkp@intel.com/

All warnings (new ones prefixed by >>):

   drivers/cdx/cdx.c:473:10: warning: variable 'len' set but not used [-Wunused-but-set-variable]
     473 |         ssize_t len;
         |                 ^
>> drivers/cdx/cdx.c:478:1: warning: non-void function does not return a value [-Wreturn-type]
     478 | }
         | ^
   2 warnings generated.


vim +478 drivers/cdx/cdx.c

48a6c7bced2a78 Nipun Gupta 2023-03-13  468  
48a6c7bced2a78 Nipun Gupta 2023-03-13  469  static ssize_t driver_override_show(struct device *dev,
48a6c7bced2a78 Nipun Gupta 2023-03-13  470  				    struct device_attribute *attr, char *buf)
48a6c7bced2a78 Nipun Gupta 2023-03-13  471  {
48a6c7bced2a78 Nipun Gupta 2023-03-13  472  	struct cdx_device *cdx_dev = to_cdx_device(dev);
4228bb0224f83f Qiu-ji Chen 2025-01-15  473  	ssize_t len;
48a6c7bced2a78 Nipun Gupta 2023-03-13  474  
4228bb0224f83f Qiu-ji Chen 2025-01-15  475  	device_lock(dev);
4228bb0224f83f Qiu-ji Chen 2025-01-15  476  	len = sysfs_emit(buf, "%s\n", cdx_dev->driver_override);
4228bb0224f83f Qiu-ji Chen 2025-01-15  477  	device_unlock(dev);
48a6c7bced2a78 Nipun Gupta 2023-03-13 @478  }
48a6c7bced2a78 Nipun Gupta 2023-03-13  479  static DEVICE_ATTR_RW(driver_override);
48a6c7bced2a78 Nipun Gupta 2023-03-13  480  

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