Re: [PATCH] mm/kfence: fix a potential NULL pointer dereference

kernel test robot
2022-04-27T12:18:36Z

Hi,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on hnaz-mm/master]

url: https://github.com/intel-lab-lkp/linux/commits/cgel-zte-gmail-com/mm-kfence-fix-a-potential-NULL-pointer-dereference/20220427-151258
base: https://github.com/hnaz/linux-mm master
config: x86_64-randconfig-a014 (https://download.01.org/0day-ci/archive/20220427/202204272015.3JRd9BKR-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 1cddcfdc3c683b393df1a5c9063252eb60e52818)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/920e9e639493bc72bee803c763f09760e3acd063
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review cgel-zte-gmail-com/mm-kfence-fix-a-potential-NULL-pointer-dereference/20220427-151258
git checkout 920e9e639493bc72bee803c763f09760e3acd063
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

>> mm/kfence/core.c:1067:23: error: use of undeclared identifier 'addr'
kfence_guarded_free(addr, meta, false);
^
mm/kfence/core.c:1075:23: warning: incompatible pointer to integer conversion passing 'void *' to parameter of type 'unsigned long' [-Wint-conversion]
kfence_report_error(addr, false, NULL, NULL, KFENCE_ERROR_INVALID);
^~~~
mm/kfence/kfence.h:129:40: note: passing argument to parameter 'address' here
void kfence_report_error(unsigned long address, bool is_write, struct pt_regs *regs,
^
1 warning and 1 error generated.

vim +/addr +1067 mm/kfence/core.c

0ce20dd840897b1 Alexander Potapenko 2021-02-25 1050
0ce20dd840897b1 Alexander Potapenko 2021-02-25 1051
920e9e639493bc7 xu xin 2022-04-27 1052 /* Require: meta is not NULL*/
920e9e639493bc7 xu xin 2022-04-27 1053 static __always_inline void __try_free_kfence_meta(struct kfence_metadata *meta)
920e9e639493bc7 xu xin 2022-04-27 1054 {
8f0b36497303487 Muchun Song 2022-04-01 1055 #ifdef CONFIG_MEMCG
8f0b36497303487 Muchun Song 2022-04-01 1056 KFENCE_WARN_ON(meta->objcg);
8f0b36497303487 Muchun Song 2022-04-01 1057 #endif
0ce20dd840897b1 Alexander Potapenko 2021-02-25 1058 /*
0ce20dd840897b1 Alexander Potapenko 2021-02-25 1059 * If the objects of the cache are SLAB_TYPESAFE_BY_RCU, defer freeing
0ce20dd840897b1 Alexander Potapenko 2021-02-25 1060 * the object, as the object page may be recycled for other-typed
0ce20dd840897b1 Alexander Potapenko 2021-02-25 1061 * objects once it has been freed. meta->cache may be NULL if the cache
0ce20dd840897b1 Alexander Potapenko 2021-02-25 1062 * was destroyed.
0ce20dd840897b1 Alexander Potapenko 2021-02-25 1063 */
0ce20dd840897b1 Alexander Potapenko 2021-02-25 1064 if (unlikely(meta->cache && (meta->cache->flags & SLAB_TYPESAFE_BY_RCU)))
0ce20dd840897b1 Alexander Potapenko 2021-02-25 1065 call_rcu(&meta->rcu_head, rcu_guarded_free);
0ce20dd840897b1 Alexander Potapenko 2021-02-25 1066 else
0ce20dd840897b1 Alexander Potapenko 2021-02-25 @1067 kfence_guarded_free(addr, meta, false);
0ce20dd840897b1 Alexander Potapenko 2021-02-25 1068 }
0ce20dd840897b1 Alexander Potapenko 2021-02-25 1069