On Fri, Aug 07, 2020 at 12:05:27AM +0900, Eiichi Tsukata wrote:
> If xfs_sysfs_init is called with parent_kobj == NULL, UBSAN
> shows the following warning:
This needs to be sent to the xfs mailing list, per get_maintainers.pl.
--D
> UBSAN: null-ptr-deref in ./fs/xfs/xfs_sysfs.h:37:23
> member access within null pointer of type 'struct xfs_kobj'
> Call Trace:
> dump_stack+0x10e/0x195
> ubsan_type_mismatch_common+0x241/0x280
> __ubsan_handle_type_mismatch_v1+0x32/0x40
> init_xfs_fs+0x12b/0x28f
> do_one_initcall+0xdd/0x1d0
> do_initcall_level+0x151/0x1b6
> do_initcalls+0x50/0x8f
> do_basic_setup+0x29/0x2b
> kernel_init_freeable+0x19f/0x20b
> kernel_init+0x11/0x1e0
> ret_from_fork+0x22/0x30
>
> Fix it by checking parent_kobj before the code accesses its member.
>
> Signed-off-by: Eiichi Tsukata <devel@xxxxxxxxxxxx>
> ---
> fs/xfs/xfs_sysfs.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/xfs/xfs_sysfs.h b/fs/xfs/xfs_sysfs.h
> index e9f810fc6731..aad67dc4ab5b 100644
> --- a/fs/xfs/xfs_sysfs.h
> +++ b/fs/xfs/xfs_sysfs.h
> @@ -32,9 +32,9 @@ xfs_sysfs_init(
> struct xfs_kobj *parent_kobj,
> const char *name)
> {
> + struct kobject *parent = parent_kobj ? &parent_kobj->kobject : NULL;
> init_completion(&kobj->complete);
> - return kobject_init_and_add(&kobj->kobject, ktype,
> - &parent_kobj->kobject, "%s", name);
> + return kobject_init_and_add(&kobj->kobject, ktype, parent, "%s", name);
> }
>
> static inline void
> --
> 2.26.2
>
