Re: [PATCH v2] ext4: fix potential use after free in system zone via remount with noblock_validity

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

Hi "zhangyi,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on linus/master]
[cannot apply to v5.3-rc3 next-20190807]
[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/zhangyi-F/ext4-fix-potential-use-after-free-in-system-zone-via-remount-with-noblock_validity/20190804-163619
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.1-rc1-7-g2b96cd8-dirty
        make ARCH=x86_64 allmodconfig
        make C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__'

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


sparse warnings: (new ones prefixed by >>)

   include/linux/sched.h:609:43: sparse: sparse: bad integer constant expression
   include/linux/sched.h:609:73: sparse: sparse: invalid named zero-width bitfield `value'
   include/linux/sched.h:610:43: sparse: sparse: bad integer constant expression
   include/linux/sched.h:610:67: sparse: sparse: invalid named zero-width bitfield `bucket_id'
   include/linux/rbtree.h:84:9: sparse: sparse: incompatible types in comparison expression (different address spaces):
   include/linux/rbtree.h:84:9: sparse:    struct rb_node [noderef] <asn:4> *
   include/linux/rbtree.h:84:9: sparse:    struct rb_node *
>> fs/ext4/block_validity.c:252:9: sparse: sparse: incompatible types in comparison expression (different address spaces):
>> fs/ext4/block_validity.c:252:9: sparse:    struct rb_node [noderef] <asn:4> *
>> fs/ext4/block_validity.c:252:9: sparse:    struct rb_node *

vim +252 fs/ext4/block_validity.c

   246	
   247	/* Called when the filesystem is unmounted */
   248	void ext4_release_system_zone(struct super_block *sb)
   249	{
   250		struct ext4_system_zone	*entry, *n;
   251	
 > 252		rcu_assign_pointer(EXT4_SB(sb)->system_blks.rb_node, NULL);
   253	
   254		rbtree_postorder_for_each_entry_safe(entry, n,
   255				&EXT4_SB(sb)->system_blks, node)
   256			call_rcu(&entry->rcu, destroy_system_zone);
   257	}
   258	

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