RDMA/mlx5: Fix a race for an ODP MR which leads to CQE with error

Overview

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

RDMA/mlx5: Fix a race for an ODP MR which leads to CQE with error

This patch addresses a race condition for an ODP MR that can result in a CQE with an error on the UMR QP.

During the __mlx5_ib_dereg_mr() flow, the following sequence of calls occurs:

mlx5_revoke_mr() mlx5r_umr_revoke_mr() mlx5r_umr_post_send_wait()

At this point, the lkey is freed from the hardware's perspective.

However, concurrently, mlx5_ib_invalidate_range() might be triggered by another task attempting to invalidate a range for the same freed lkey.

This task will:

• Acquire the umem_odp->umem_mutex lock.
• Call mlx5r_umr_update_xlt() on the UMR QP.
• Since the lkey has already been freed, this can lead to a CQE error, causing the UMR QP to enter an error state [1].

To resolve this race condition, the umem_odp->umem_mutex lock is now also acquired as part of the mlx5_revoke_mr() scope. Upon successful revoke, we set umem_odp->private which points to that MR to NULL, preventing any further invalidation attempts on its lkey.

[1] From dmesg:

infiniband rocep8s0f0: dump_cqe:277:(pid 0): WC error: 6, Message: memory bind operation error cqe_dump: 00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 cqe_dump: 00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 cqe_dump: 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 cqe_dump: 00000030: 00 00 00 00 08 00 78 06 25 00 11 b9 00 0e dd d2

WARNING: CPU: 15 PID: 1506 at drivers/infiniband/hw/mlx5/umr.c:394 mlx5r_umr_post_send_wait+0x15a/0x2b0 [mlx5_ib] Modules linked in: ip6table_mangle ip6table_natip6table_filter ip6_tables iptable_mangle 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 rdma_cm iw_cm ib_umad ib_ipoib ib_cm mlx5_ib ib_uverbs ib_core fuse mlx5_core CPU: 15 UID: 0 PID: 1506 Comm: ibv_rc_pingpong Not tainted 6.12.0-rc7+ #1626 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 RIP: 0010:mlx5r_umr_post_send_wait+0x15a/0x2b0 [mlx5_ib] [..] Call Trace: <TASK> mlx5r_umr_update_xlt+0x23c/0x3e0 [mlx5_ib] mlx5_ib_invalidate_range+0x2e1/0x330 [mlx5_ib] __mmu_notifier_invalidate_range_start+0x1e1/0x240 zap_page_range_single+0xf1/0x1a0 madvise_vma_behavior+0x677/0x6e0 do_madvise+0x1a2/0x4b0 __x64_sys_madvise+0x25/0x30 do_syscall_64+0x6b/0x140 entry_SYSCALL_64_after_hwframe+0x76/0x7e

Affected

• Linux >= e6fb246ccafbdfc86e0750af021628132fdbceac < 63126215de7beebb662fcef7c7558c795000c904
• Linux >= e6fb246ccafbdfc86e0750af021628132fdbceac < b13d32786acabf70a7b04ed24b7468fc3c82977c
• Linux >= e6fb246ccafbdfc86e0750af021628132fdbceac < 5297f5ddffef47b94172ab0d3d62270002a3dcc1
• Linux >= e6fb246ccafbdfc86e0750af021628132fdbceac < abb604a1a9c87255c7a6f3b784410a9707baf467
• Linux 5.13

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.