CVE-2024-35902 Information

May 20, 2024 cve

Description

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

Reference

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