6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mahmoud Adam <mngyadam@xxxxxxxxxx> commit 62fc3357e079a07a22465b9b6ef71bb6ea75ee4b upstream. 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 Fixes: c055fc00c07b ("net/rds: fix WARNING in rds_conn_connect_if_down") Cc: stable@xxxxxxxxxxxxxxx # v4.19+ Signed-off-by: Mahmoud Adam <mngyadam@xxxxxxxxxx> Reviewed-by: Simon Horman <horms@xxxxxxxxxx> Link: https://lore.kernel.org/r/20240326153132.55580-1-mngyadam@xxxxxxxxxx Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/rds/rdma.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/rds/rdma.c +++ b/net/rds/rdma.c @@ -302,7 +302,7 @@ static int __rds_rdma_map(struct rds_soc } ret = PTR_ERR(trans_private); /* Trigger connection so that its ready for the next retry */ - if (ret == -ENODEV) + if (ret == -ENODEV && cp) rds_conn_connect_if_down(cp->cp_conn); goto out; }