On Sat, Sep 6, 2025 at 4:24 AM Nathan Chancellor wrote:
When accessing one of the files under /sys/fs/nilfs2/features when CONFIG_CFI_CLANG is enabled, there is a CFI violation:
CFI failure at kobj_attr_show+0x59/0x80 (target: nilfs_feature_revision_show+0x0/0x30; expected type: 0xfc392c4d) ... Call Trace:
<TASK> sysfs_kf_seq_show+0x2a6/0x390 ? __cfi_kobj_attr_show+0x10/0x10 kernfs_seq_show+0x104/0x15b seq_read_iter+0x580/0xe2b ...
When the kobject of the kset for /sys/fs/nilfs2 is initialized, its ktype is set to kset_ktype, which has a ->sysfs_ops of kobj_sysfs_ops. When nilfs_feature_attr_group is added to that kobject via sysfs_create_group(), the kernfs_ops of each files is sysfs_file_kfops_rw, which will call sysfs_kf_seq_show() when ->seq_show() is called. sysfs_kf_seq_show() in turn calls kobj_attr_show() through ->sysfs_ops->show(). kobj_attr_show() casts the provided attribute out to a 'struct kobj_attribute' via container_of() and calls ->show(), resulting in the CFI violation since neither nilfs_feature_revision_show() nor nilfs_feature_README_show() match the prototype of ->show() in 'struct kobj_attribute'.
Resolve the CFI violation by adjusting the second parameter in nilfs_feature_{revision,README}_show() from 'struct attribute' to 'struct kobj_attribute' to match the expected prototype.
Cc: stable@vger.kernel.org Fixes: aebe17f68444 ("nilfs2: add /sys/fs/nilfs2/features group") Reported-by: kernel test robot oliver.sang@intel.com Closes: https://lore.kernel.org/oe-lkp/202509021646.bc78d9ef-lkp@intel.com/ Signed-off-by: Nathan Chancellor nathan@kernel.org
Thanks again! I'll send this upstream.
Regards, Ryusuke Konishi