Description

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

net/mlx5e: Fix peer flow lists handling

The cited change refactored mlx5e_tc_del_fdb_peer_flow() to only clear DUP
flag when list of peer flows has become empty. However, if any concurrent
user holds a reference to a peer flow (for example, the neighbor update
workqueue task is updating peer flow's parent encap entry concurrently),
then the flow will not be removed from the peer list and, consecutively,
DUP flag will remain set. Since mlx5e_tc_del_fdb_peers_flow() calls
mlx5e_tc_del_fdb_peer_flow() for every possible peer index the algorithm
will try to remove the flow from eswitch instances that it has never peered
with causing either NULL pointer dereference when trying to remove the flow
peer list head of peer_index that was never initialized or a warning if the
list debug config is enabled[0].

Fix the issue by always removing the peer flow from the list even when not
releasing the last reference to it.

[0]:

[ 3102.985806] ------------[ cut here ]------------
[ 3102.986223] list_del corruption, ffff888139110698->next is NULL
[ 3102.986757] WARNING: CPU: 2 PID: 22109 at lib/list_debug.c:53 __list_del_entry_valid_or_report+0x4f/0xc0
[ 3102.987561] Modules linked in: act_ct nf_flow_table bonding act_tunnel_key act_mirred act_skbedit vxlan cls_matchall nfnetlink_cttimeout act_gact cls_flower sch_ingress mlx5_vdpa vringh vhost_iotlb vdpa openvswitch nsh xt_MASQUERADE nf_conntrack_netlink nfnetlink iptab...

Classification

CVE ID: CVE-2023-52487

Affected Products

Vendor: Linux

Product: Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.04% (probability of being exploited)

EPSS Percentile: 5.08% (scored less or equal to compared to others)

EPSS Date: 2025-02-04 (when was this score calculated)

References

https://git.kernel.org/stable/c/74cec142f89bf85c6c99c5db957da9f663f9f16f
https://git.kernel.org/stable/c/e24d6f5a7f2d95a98a46257a5a5a5381d572894f
https://git.kernel.org/stable/c/d76fdd31f953ac5046555171620f2562715e9b71

Timeline