Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

net/mlx5: fs, lock FTE when checking if active

The referenced commits introduced a two-step process for deleting FTEs:

- Lock the FTE, delete it from hardware, set the hardware deletion function to NULL and unlock the FTE. - Lock the parent flow group, delete the software copy of the FTE, and remove it from the xarray.

However, this approach encounters a race condition if a rule with the same match value is added simultaneously. In this scenario, fs_core may set the hardware deletion function to NULL prematurely, causing a panic during subsequent rule deletions.

To prevent this, ensure the active flag of the FTE is checked under a lock, which will prevent the fs_core layer from attaching a new steering rule to an FTE that is in the process of deletion.

[ 438.967589] MOSHE: 2496 mlx5_del_flow_rules del_hw_func [ 438.968205] ------------[ cut here ]------------ [ 438.968654] refcount_t: decrement hit 0; leaking memory. [ 438.969249] WARNING: CPU: 0 PID: 8957 at lib/refcount.c:31 refcount_warn_saturate+0xfb/0x110 [ 438.970054] Modules linked in: act_mirred cls_flower act_gact sch_ingress openvswitch nsh mlx5_vdpa vringh vhost_iotlb vdpa mlx5_ib mlx5_core xt_conntrack xt_MASQUERADE nf_conntrack_netlink nfnetlink xt_addrtype iptable_nat nf_nat br_netfilter rpcsec_gss_krb5 auth_rpcgss oid_registry overlay rpcrdma rdma_ucm ib_iser libiscsi scsi_transport_iscsi ib_umad rdma_cm ib_ipoib iw_cm ib_cm ib_…