On Thu, 2021-08-05 at 05:20 -0700, Tuo Li wrote:
> kcalloc() is called to allocate memory for m->m_info, and if it fails,
> ceph_mdsmap_destroy() behind the label out_err will be called:
> ceph_mdsmap_destroy(m);
>
> In ceph_mdsmap_destroy(), m->m_info is dereferenced through:
> kfree(m->m_info[i].export_targets);
>
> To fix this possible null-pointer dereference, if memory allocation
> for m->m_info fails, free m and return -ENOMEM.
>
> Reported-by: TOTE Robot <oslab@xxxxxxxxxxxxxxx>
> Signed-off-by: Tuo Li <islituo@xxxxxxxxx>
> ---
> fs/ceph/mdsmap.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ceph/mdsmap.c b/fs/ceph/mdsmap.c
> index abd9af7727ad..7d73e4b64b12 100644
> --- a/fs/ceph/mdsmap.c
> +++ b/fs/ceph/mdsmap.c
> @@ -166,8 +166,10 @@ struct ceph_mdsmap *ceph_mdsmap_decode(void **p, void *end, bool msgr2)
> m->possible_max_rank = max(m->m_num_active_mds, m->m_max_mds);
>
> m->m_info = kcalloc(m->possible_max_rank, sizeof(*m->m_info), GFP_NOFS);
> - if (!m->m_info)
> - goto nomem;
> + if (!m->m_info) {
> + kfree(m);
> + return ERR_PTR(-ENOMEM);
> + }
>
> /* pick out active nodes from mds_info (state > 0) */
> for (i = 0; i < n; i++) {
Good catch. This function is already pretty complex. How about we
instead fix this in ceph_mdsmap_destroy and make it safe to call that
with the mdsmap in this state?
Basically, just put an "if (m->m_info)" around the for loop in that
function. Sound ok?
--
Jeff Layton <jlayton@xxxxxxxxxx>
