Re: [PATCH v1] rpmsg: char: fix use-after-free on probe error path

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

Hi Yuho,

kernel test robot noticed the following build warnings:

[auto build test WARNING on remoteproc/rpmsg-next]
[also build test WARNING on linus/master v7.0 next-20260422]
[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/Yuho-Choi/rpmsg-char-fix-use-after-free-on-probe-error-path/20260421-073128
base:   https://git.kernel.org/pub/scm/linux/kernel/git/remoteproc/linux.git rpmsg-next
patch link:    https://lore.kernel.org/r/20260416042338.10146-1-dbgh9129%40gmail.com
patch subject: [PATCH v1] rpmsg: char: fix use-after-free on probe error path
config: alpha-allyesconfig (https://download.01.org/0day-ci/archive/20260422/202604222350.v3J2LzRi-lkp@intel.com/config)
compiler: alpha-linux-gcc (GCC) 15.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260422/202604222350.v3J2LzRi-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/202604222350.v3J2LzRi-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from include/linux/compiler.h:372,
                    from include/linux/build_bug.h:5,
                    from include/linux/container_of.h:5,
                    from include/linux/list.h:5,
                    from include/linux/kobject.h:19,
                    from include/linux/cdev.h:5,
                    from drivers/rpmsg/rpmsg_char.c:17:
>> arch/alpha/include/asm/rwonce.h:23:9: warning: '__READ_ONCE' redefined
      23 | #define __READ_ONCE(x)                                                  \
         |         ^~~~~~~~~~~
   In file included from drivers/rpmsg/rpmsg_char.c:14:
   include/asm-generic/rwonce.h:44:9: note: this is the location of the previous definition
      44 | #define __READ_ONCE(x)  (*(const volatile __unqual_scalar_typeof(x) *)&(x))
         |         ^~~~~~~~~~~


vim +/__READ_ONCE +23 arch/alpha/include/asm/rwonce.h

d6462858851549c Will Deacon 2019-10-30  11  
d6462858851549c Will Deacon 2019-10-30  12  /*
d6462858851549c Will Deacon 2019-10-30  13   * Alpha is apparently daft enough to reorder address-dependent loads
d6462858851549c Will Deacon 2019-10-30  14   * on some CPU implementations. Knock some common sense into it with
d6462858851549c Will Deacon 2019-10-30  15   * a memory barrier in READ_ONCE().
d6462858851549c Will Deacon 2019-10-30  16   *
d6462858851549c Will Deacon 2019-10-30  17   * For the curious, more information about this unusual reordering is
d6462858851549c Will Deacon 2019-10-30  18   * available in chapter 15 of the "perfbook":
d6462858851549c Will Deacon 2019-10-30  19   *
d6462858851549c Will Deacon 2019-10-30  20   *  https://kernel.org/pub/linux/kernel/people/paulmck/perfbook/perfbook.html
d6462858851549c Will Deacon 2019-10-30  21   *
d6462858851549c Will Deacon 2019-10-30  22   */
d6462858851549c Will Deacon 2019-10-30 @23  #define __READ_ONCE(x)							\
d6462858851549c Will Deacon 2019-10-30  24  ({									\
d6462858851549c Will Deacon 2019-10-30  25  	__unqual_scalar_typeof(x) __x =					\
d6462858851549c Will Deacon 2019-10-30  26  		(*(volatile typeof(__x) *)(&(x)));			\
d6462858851549c Will Deacon 2019-10-30  27  	mb();								\
d6462858851549c Will Deacon 2019-10-30  28  	(typeof(x))__x;							\
d6462858851549c Will Deacon 2019-10-30  29  })
d6462858851549c Will Deacon 2019-10-30  30  

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