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: [email protected]
> Fixes: aebe17f68444 ("nilfs2: add /sys/fs/nilfs2/features group")
> Reported-by: kernel test robot <[email protected]>
> Closes: https://lore.kernel.org/oe-lkp/[email protected]/
> Signed-off-by: Nathan Chancellor <[email protected]>
Thanks again!
I'll send this upstream.
Regards,
Ryusuke Konishi
