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Medium severity5.5NVD Advisory· Published Nov 5, 2024· Updated May 12, 2026

CVE-2024-50095

CVE-2024-50095

Description

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

RDMA/mad: Improve handling of timed out WRs of mad agent

Current timeout handler of mad agent acquires/releases mad_agent_priv lock for every timed out WRs. This causes heavy locking contention when higher no. of WRs are to be handled inside timeout handler.

This leads to softlockup with below trace in some use cases where rdma-cm path is used to establish connection between peer nodes

Trace: ----- BUG: soft lockup - CPU#4 stuck for 26s! [kworker/u128:3:19767] CPU: 4 PID: 19767 Comm: kworker/u128:3 Kdump: loaded Tainted: G OE ------- --- 5.14.0-427.13.1.el9_4.x86_64 #1 Hardware name: Dell Inc. PowerEdge R740/01YM03, BIOS 2.4.8 11/26/2019 Workqueue: ib_mad1 timeout_sends [ib_core] RIP: 0010:__do_softirq+0x78/0x2ac RSP: 0018:ffffb253449e4f98 EFLAGS: 00000246 RAX: 00000000ffffffff RBX: 0000000000000000 RCX: 000000000000001f RDX: 000000000000001d RSI: 000000003d1879ab RDI: fff363b66fd3a86b RBP: ffffb253604cbcd8 R08: 0000009065635f3b R09: 0000000000000000 R10: 0000000000000040 R11: ffffb253449e4ff8 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000040 FS: 0000000000000000(0000) GS:ffff8caa1fc80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fd9ec9db900 CR3: 0000000891934006 CR4: 00000000007706e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace:

? show_trace_log_lvl+0x1c4/0x2df ? show_trace_log_lvl+0x1c4/0x2df ? __irq_exit_rcu+0xa1/0xc0 ? watchdog_timer_fn+0x1b2/0x210 ? __pfx_watchdog_timer_fn+0x10/0x10 ? __hrtimer_run_queues+0x127/0x2c0 ? hrtimer_interrupt+0xfc/0x210 ? __sysvec_apic_timer_interrupt+0x5c/0x110 ? sysvec_apic_timer_interrupt+0x37/0x90 ? asm_sysvec_apic_timer_interrupt+0x16/0x20 ? __do_softirq+0x78/0x2ac ? __do_softirq+0x60/0x2ac __irq_exit_rcu+0xa1/0xc0 sysvec_call_function_single+0x72/0x90

asm_sysvec_call_function_single+0x16/0x20 RIP: 0010:_raw_spin_unlock_irq+0x14/0x30 RSP: 0018:ffffb253604cbd88 EFLAGS: 00000247 RAX: 000000000001960d RBX: 0000000000000002 RCX: ffff8cad2a064800 RDX: 000000008020001b RSI: 0000000000000001 RDI: ffff8cad5d39f66c RBP: ffff8cad5d39f600 R08: 0000000000000001 R09: 0000000000000000 R10: ffff8caa443e0c00 R11: ffffb253604cbcd8 R12: ffff8cacb8682538 R13: 0000000000000005 R14: ffffb253604cbd90 R15: ffff8cad5d39f66c cm_process_send_error+0x122/0x1d0 [ib_cm] timeout_sends+0x1dd/0x270 [ib_core] process_one_work+0x1e2/0x3b0 ? __pfx_worker_thread+0x10/0x10 worker_thread+0x50/0x3a0 ? __pfx_worker_thread+0x10/0x10 kthread+0xdd/0x100 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x29/0x50

Simplified timeout handler by creating local list of timed out WRs and invoke send handler post creating the list. The new method acquires/ releases lock once to fetch the list and hence helps to reduce locking contetiong when processing higher no. of WRs

AI Insight

LLM-synthesized narrative grounded in this CVE's description and references.

A locking contention bug in the Linux kernel's RDMA MAD timeout handler can cause soft lockups during high-volume RDMA communication.

Description

The vulnerability is a locking contention issue in the Linux kernel's RDMA (Remote Direct Memory Access) management datagram (MAD) agent. The timeout handler for timed-out work requests (WRs) acquires and releases the mad_agent_priv lock for every individual timed-out WR. When a large number of WRs need handling, this per-WR locking creates heavy contention, leading to a soft lockup condition. The official kernel description notes that the soft lockup occurs on CPU#4 for 26 seconds in a scenario using the rdma-cm path for peer node connections [3][4].

Exploitation

No special authentication or network position is required beyond normal RDMA operation. The issue is triggered when the MAD agent manages numerous concurrent timed-out WRs, which can happen during regular high-throughput RDMA communication, such as establishing connections via rdma-cm. An attacker with local access or the ability to influence RDMA traffic rates could potentially induce the condition, but the primary trigger is a legitimate high-volume workload [1][2].

Impact

The impact is a denial of service (DoS) condition within the kernel, resulting in a soft lockup that hangs the affected CPU for an extended period (26 seconds observed). This can disrupt all RDMA operations on that system, potentially causing connection failures, timeouts, and overall system instability. The CVSS v3 base score is 5.5 (Medium), with the vector indicating local access and low privileges required [1][2].

Mitigation

The fix has been applied in the Linux kernel stable branches. The commit addresses the locking issue by optimizing the timeout handler to reduce lock contention. Users should update their kernel to a version containing the fix. For Siemens industrial products listed in related advisories (e.g., SIMATIC S7-1500 TM MFP GNU/Linux subsystem), the vendor provides updates as part of its security advisory process [1][2]. The exact commit IDs are available in the kernel stable repository [3][4].

References
  1. SSA-355557
  2. SSA-265688
  3. Making sure you're not a bot!
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AI Insight generated on May 20, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.

Affected products

114

Patches

0

No patches discovered yet.

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References

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