Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
net/rds: fix possible cp null dereference
cp might be null, calling cp->cp_conn would produce null dereference
[Simon Horman adds:]
Analysis:
-
cp is a parameter of __rds_rdma_map and is not reassigned.
-
The following call-sites pass a NULL cp argument to __rds_rdma_map()
- rds_get_mr()
- rds_get_mr_for_dest
- Prior to the code above, the following assumes that cp may be NULL (which is indicative, but could itself be unnecessary)
trans_private = rs->rs_transport->get_mr( sg, nents, rs, &mr->r_key, cp ? cp->cp_conn : NULL, args->vec.addr, args->vec.bytes, need_odp ? ODP_ZEROBASED : ODP_NOT_NEEDED);
- The code modified by this patch is guarded by IS_ERR(trans_private), where trans_private is assigned as per the previous point in this analysis.
The only implementation of get_mr that I could locate is rds_ib_get_mr() which can return an ERR_PTR if the conn (4th) argument is NULL.
- ret is set to PTR_ERR(trans_private). rds_ib_get_mr can return ERR_PTR(-ENODEV) if the conn (4th) argument is NULL. Thus ret may be -ENODEV in which case the code in question will execute.
Conclusion:
- cp may be NULL at the point where this patch adds a check; this patch does seem to address a possible bug
Details
- Affected product:
- Ubuntu 16.04 ELS , Ubuntu 18.04 ELS
- Affected packages:
- linux-hwe @ 4.15.0 (+1 more)
In the Linux kernel, the following vulnerability has been resolved:
net/rds: fix possible cp null dereference
cp might be null, calling cp->cp_conn would produce null dereference
[Simon Horman adds:]
Analysis:
-
cp is a parameter of __rds_rdma_map and is not reassigned.
-
The following call-sites pass a NULL cp argument to __rds_rdma_map()
- rds_get_mr()
- rds_get_mr_for_dest
- Prior to the code above, the following assumes that cp may be NULL (which is indicative, but could itself be unnecessary)
trans_private = rs->rs_transport->get_mr( sg, nents, rs, &mr->r_key, cp ? cp->cp_conn : NULL, args->vec.addr, args->vec.bytes, need_odp ? ODP_ZEROBASED : ODP_NOT_NEEDED);
- The code modified by this patch is guarded by IS_ERR(trans_private), where trans_private is assigned as per the previous point in this analysis.
The only implementation of get_mr that I could locate is rds_ib_get_mr() which can return an ERR_PTR if the conn (4th) argument is NULL.
- ret is set to PTR_ERR(trans_private). rds_ib_get_mr can return ERR_PTR(-ENODEV) if the conn (4th) argument is NULL. Thus ret may be -ENODEV in which case the code in question will execute.
Conclusion:
- cp may be NULL at the point where this patch adds a check; this patch does seem to address a possible bug