--- id: CVE-2023-53591 title: 'net/mlx5e: Fix deadlock in tc route query code' summary: |- In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: Fix deadlock in tc route query code Cited commit causes ABBA deadlock[0] when peer flows are created while holding the devcom rw semaphore. Due to peer flow… severity: none vendor: Linux product: Linux affected: - >- Linux >= f9d196bd632b8b79261ec3366c30ec3923ea9a02 < 69966bce28da6aadccfd968b75d128a79da32d17 - >- Linux >= f9d196bd632b8b79261ec3366c30ec3923ea9a02 < 362063df6ceec80b0b6798b61ae03504dcc125a5 - >- Linux >= f9d196bd632b8b79261ec3366c30ec3923ea9a02 < a7236e420a7d8082b1df4b3e05c739dd2642a662 - >- Linux >= f9d196bd632b8b79261ec3366c30ec3923ea9a02 < 691c041bf20899fc13c793f92ba61ab660fa3a30 - Linux 87a0625cf1c76caeaa15c576a0b2fcad4b9387d0 - Linux 7778fe1a6a6c069a460e4e3ff8ed3722392a4b5b - Linux >= 5.13.17 < 5.14 - Linux >= 5.14.4 < 5.15 - Linux 5.15 ssvc: exploitation: none automatable: 'no' technicalImpact: partial timestamp: '2026-11-05T20:24:41.149943Z' published: '2025-10-04' updated: '2026-11-05' sourceUpdated: '2026-11-05T20:31:16.021Z' source: CVEORG sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2023-53591' references: - url: 'https://git.kernel.org/stable/c/69966bce28da6aadccfd968b75d128a79da32d17' - url: 'https://git.kernel.org/stable/c/362063df6ceec80b0b6798b61ae03504dcc125a5' - url: 'https://git.kernel.org/stable/c/a7236e420a7d8082b1df4b3e05c739dd2642a662' - url: 'https://git.kernel.org/stable/c/691c041bf20899fc13c793f92ba61ab660fa3a30' tags: - cve.org epss: 0.00131 epssPercentile: 0.02698 ingestedAt: '2026-11-05T22:38:31.812Z' --- ## Overview In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: Fix deadlock in tc route query code Cited commit causes ABBA deadlock[0] when peer flows are created while holding the devcom rw semaphore. Due to peer flows offload implementation the lock is taken much higher up the call chain and there is no obvious way to easily fix the deadlock. Instead, since tc route query code needs the peer eswitch structure only to perform a lookup in xarray and doesn't perform any sleeping operations with it, refactor the code for lockless execution in following ways: - RCUify the devcom 'data' pointer. When resetting the pointer synchronously wait for RCU grace period before returning. This is fine since devcom is currently only used for synchronization of pairing/unpairing of eswitches which is rare and already expensive as-is. - Wrap all usages of 'paired' boolean in {READ|WRITE}_ONCE(). The flag has already been used in some unlocked contexts without proper annotations (e.g. users of mlx5_devcom_is_paired() function), but it wasn't an issue since all relevant code paths checked it again after obtaining the devcom semaphore. Now it is also used by mlx5_devcom_get_peer_data_rcu() as "best effort" check to return NULL when devcom is being unpaired. Note that while RCU read lock doesn't prevent the unpaired flag from being changed concurrently it still guarantees that reader can continue to use 'data'. - Refactor mlx5e_tc_query_route_vport() function to use new mlx5_devcom_get_peer_data_rcu() API which fixes the deadlock. [0]: [ 164.599612] ====================================================== [ 164.600142] WARNING: possible circular locking dependency detected [ 164.600667] 6.3.0-rc3+ #1 Not tainted [ 164.601021] ------------------------------------------------------ [ 164.601557] handler1/3456 is trying to acquire lock: [ 164.601998] ffff88811f1714b0 (&esw->offloads.encap_tbl_lock){+.+.}-{3:3}, at: mlx5e_attach_encap+0xd8/0x8b0 [mlx5_core] [ 164.603078] but task is already holding lock: [ 164.603617] ffff88810137fc98 (&comp->sem){++++}-{3:3}, at: mlx5_devcom_get_peer_data+0x37/0x80 [mlx5_core] [ 164.604459] which lock already depends on the new lock. [ 164.605190] the existing dependency chain (in reverse order) is: [ 164.605848] -> #1 (&comp->sem){++++}-{3:3}: [ 164.606380] down_read+0x39/0x50 [ 164.606772] mlx5_devcom_get_peer_data+0x37/0x80 [mlx5_core] [ 164.607336] mlx5e_tc_query_route_vport+0x86/0xc0 [mlx5_core] [ 164.607914] mlx5e_tc_tun_route_lookup+0x1a4/0x1d0 [mlx5_core] [ 164.608495] mlx5e_attach_decap_route+0xc6/0x1e0 [mlx5_core] [ 164.609063] mlx5e_tc_add_fdb_flow+0x1ea/0x360 [mlx5_core] [ 164.609627] __mlx5e_add_fdb_flow+0x2d2/0x430 [mlx5_core] [ 164.610175] mlx5e_configure_flower+0x952/0x1a20 [mlx5_core] [ 164.610741] tc_setup_cb_add+0xd4/0x200 [ 164.611146] fl_hw_replace_filter+0x14c/0x1f0 [cls_flower] [ 164.611661] fl_change+0xc95/0x18a0 [cls_flower] [ 164.612116] tc_new_tfilter+0x3fc/0xd20 [ 164.612516] rtnetlink_rcv_msg+0x418/0x5b0 [ 164.612936] netlink_rcv_skb+0x54/0x100 [ 164.613339] netlink_unicast+0x190/0x250 [ 164.613746] netlink_sendmsg+0x245/0x4a0 [ 164.614150] sock_sendmsg+0x38/0x60 [ 164.614522] ____sys_sendmsg+0x1d0/0x1e0 [ 164.614934] ___sys_sendmsg+0x80/0xc0 [ 164.615320] __sys_sendmsg+0x51/0x90 [ 164.615701] do_syscall_64+0x3d/0x90 [ 164.616083] entry_SYSCALL_64_after_hwframe+0x46/0xb0 [ 164.616568] -> #0 (&esw->offloads.encap_tbl_lock){+.+.}-{3:3}: [ 164.617210] __lock_acquire+0x159e/0x26e0 [ 164.617638] lock_acquire+0xc2/0x2a0 [ 164.618018] __mutex_lock+0x92/0xcd0 [ 164.618401] mlx5e_attach_encap+0xd8/0x8b0 [mlx5_core] [ 164.618943] post_process_attr+0x153/0x2d0 [ ---truncated--- ## Affected - `Linux >= f9d196bd632b8b79261ec3366c30ec3923ea9a02 < 69966bce28da6aadccfd968b75d128a79da32d17` - `Linux >= f9d196bd632b8b79261ec3366c30ec3923ea9a02 < 362063df6ceec80b0b6798b61ae03504dcc125a5` - `Linux >= f9d196bd632b8b79261ec3366c30ec3923ea9a02 < a7236e420a7d8082b1df4b3e05c739dd2642a662` - `Linux >= f9d196bd632b8b79261ec3366c30ec3923ea9a02 < 691c041bf20899fc13c793f92ba61ab660fa3a30` - `Linux 87a0625cf1c76caeaa15c576a0b2fcad4b9387d0` - `Linux 7778fe1a6a6c069a460e4e3ff8ed3722392a4b5b` - `Linux >= 5.13.17 < 5.14` - `Linux >= 5.14.4 < 5.15` - `Linux 5.15` ## Remediation Refer to the linked advisories for vendor-supplied fixes and affected version ranges.