Re: [PATCH] statx: don't leak STATX_ATTR_CHANGE_MONOTONIC in stx_attributes_mask

[Jan Kara]

On Thu 29-10-26 12:20:27, Jeff Layton wrote:
> STATX_ATTR_CHANGE_MONOTONIC is kernel-internal. cp_statx() strips it
> from stx_attributes but copies attributes_mask verbatim, so it leaks to
> userland on filesystems that advertise it (nfs, ceph), e.g.
> stx_attributes_mask = 0x8000000000b03000 on NFS.
> 
> Mask it out of stx_attributes_mask too.
> 
> Fixes: a1175d6b1bda ("vfs: plumb i_version handling into struct kstat")
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>

OK, feel free to add:

Reviewed-by: Jan Kara <jack@xxxxxxx>

								Honza

> ---
>  fs/stat.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/stat.c b/fs/stat.c
> index a2e63c6c45b7..787c13f378ff 100644
> --- a/fs/stat.c
> +++ b/fs/stat.c
> @@ -719,7 +719,7 @@ cp_statx(const struct kstat *stat, struct statx __user *buffer)
>  	tmp.stx_ino = stat->ino;
>  	tmp.stx_size = stat->size;
>  	tmp.stx_blocks = stat->blocks;
> -	tmp.stx_attributes_mask = stat->attributes_mask;
> +	tmp.stx_attributes_mask = stat->attributes_mask & ~STATX_ATTR_CHANGE_MONOTONIC;
>  	tmp.stx_atime.tv_sec = stat->atime.tv_sec;
>  	tmp.stx_atime.tv_nsec = stat->atime.tv_nsec;
>  	tmp.stx_btime.tv_sec = stat->btime.tv_sec;
> 
> ---
> base-commit: c339f4010dea8b0d754f84ace70cd1b089878ef8
> change-id: 20261029-statx-3f1d8cd8d877
> 
> Best regards,
> -- 
> Jeff Layton <jlayton@xxxxxxxxxx>
> 
-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR