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

net/smc: fix use-after-free of the LLC qentry in smc_llc_srv_add_link()

smc_llc_srv_add_link() keeps add_llc pointing into the queue entry:

add_llc = &qentry->msg.add_link; smc_llc.c:1482
...
smc_llc_save_add_link_info(link_new, add_llc); smc_llc.c:1494
smc_llc_flow_qentry_del(&lgr->llc_flow_lcl); smc_llc.c:1495
...
u8 *llc_msg = smc_link_shared_v2_rxbuf(link) ?
(u8 *)lgr->wr_rx_buf_v2 : (u8 *)add_llc; smc_llc.c:1504
smc_llc_save_add_link_rkeys(link, link_new, llc_msg); smc_llc.c:1506

smc_llc_flow_qentry_del() kfree()s the entry, so on a link without a shared
v2 receive buffer the pointer handed to smc_llc_save_add_link_rkeys() is
already freed. Before the Fixes: commit that branch always used
lgr->wr_rx_buf_v2 and add_llc was not used after the free.

Reproduced on an unpatched tree over rxe, with KASAN, kasan_multi_shot
and a link forced to max_recv_sge == 1: the entry is freed and read by
the same call, and the freeing frame is smc_llc_srv_add_link() itself.

[ 2.523161] BUG: KASAN: slab-use-after-free in smc_llc_save_add_link_rkeys+0x333/0x350
[ 2.523499] Read of size 2 at addr ffff8880052194de by task kworker/0:1/11
[ 2.523789]
[ 2.523862] CPU: 0 UID: 0 PID: 11 Comm: kworker/0:1 Not tainted 7.2.0-rc5-p0-g2c9dd296545d #35 PREEMPT(lazy)
[ 2.523865] Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[ 2.523866] Workqueue: smc_hs_wq smc_listen_work
[ 2.523869] Call Trace:
[ 2.523870] <TASK>
[ 2.523871] dump_stack_lvl+0x53/0x70
[ 2.523872] print_report+0xd0/0x630
[ 2.523874] ? __pfx__raw_spin_lock_irqsave+0x10/0x10
[ 2.523876] ? smc_llc_save_add_link_rkeys+0x333/0x350
[ 2.523878] kasan_report+0xce/0x100
[ 2.523879] ? smc_llc_save_add_link_rkeys+0x333/0x350
[ 2.523881] smc_llc_save_add_link_rkeys+0x333/0x350
[ 2.523883] ? smcr_buf_reg_lgr+0x2a4/0x660
[ 2.523885] smc_llc_srv_add_link+0xaa2/0x1e50
[ 2.523888] ? _printk+0xba/0xf0
[ 2.523897] ? __pfx_smc_llc_srv_add_link+0x10/0x10
[ 2.523899] ? down_write+0xb0/0x130
[ 2.523903] ? __pfx_down_write+0x10/0x10
[ 2.523905] smc_listen_work+0x489e/0x4d00
[ 2.523907] ? kmem_cache_free+0x1c6/0x3a0
[ 2.523911] ? __pfx_smc_listen_work+0x10/0x10
[ 2.523913] ? release_sock+0x148/0x1d0
[ 2.523915] ? smc_tcp_listen_work+0xb4f/0xfc0
[ 2.523917] ? _raw_spin_lock_irq+0x80/0xe0
[ 2.523918] ? __pfx__raw_spin_lock_irq+0x10/0x10
[ 2.523920] process_one_work+0x633/0x1030
[ 2.523922] ? assign_work+0x11d/0x370
[ 2.523924] worker_thread+0x45b/0xd10
[ 2.523926] ? __pfx_worker_thread+0x10/0x10
[ 2.523928] ? __pfx_worker_thread+0x10/0x10
[ 2.523929] kthread+0x2c6/0x3b0
[ 2.523931] ? recalc_sigpending+0x15c/0x1e0
[ 2.523934] ? __pfx_kthread+0x10/0x10
[ 2.523935] ret_from_fork+0x36e/0x5a0
[ 2.523937] ? __pfx_ret_from_fork+0x10/0x10
[ 2.523938] ? __switch_to+0x572/0xdd0
[ 2.523943] ? __pfx_kthread+0x10/0x10
[ 2.523944] ret_from_fork_asm+0x1a/0x30
[ 2.523947] </TASK>
[ 2.523948]
[ 2.531253] Allocated by task 48:
[ 2.531399] kasan_save_stack+0x33/0x60
[ 2.531570] kasan_save_track+0x14/0x30
[ 2.531737] __kasan_kmalloc+0x8f/0xa0
[ 2.531905] __kmalloc_cache_noprof+0x158/0x370
[ 2.532100] smc_llc_enqueue+0x72/0x560
[ 2.532268] smc_wr_rx_tasklet_fn+0x474/0xa80
[ 2.532491] tasklet_action_common+0x20f/0x8a0
[ 2.532714] handle_softirqs+0x18e/0x590
[ 2.532886] do_softirq+0x3b/0x60
[ 2.533036] __local_bh_enable_ip+0x61/0x70
[ 2.533221] __alloc_skb+0x732/0x890
[ 2.533384] rxe_init_packet+0x16b/0x4f0
[ 2.533567] prepare_ack_packet+0xb8/0x830
[ 2.533760] rxe_receiver+0x495/0x96e0
[ 2.533933] do_work+0x144/0x470
[ 2
---truncated---
Published: 2026-09-11
Score: 9.8 Critical
EPSS: < 1% Very Low
KEV: No
Impact: Kernel memory corruption
Action: Immediate Patch
AI Analysis

Impact

The vulnerability is a use‑after‑free in the Linux kernel’s SMC (Secure Monitor Call) subsystem. During the addition of an LLC link, the code keeps a pointer to a queue entry, frees the entry, and then later accesses that freed memory. This causes a crash or, if further exploited, elevating-825: Improper Management of Resources leading to a Use‑After‑Free condition.

Affected Systems

All Linux kernel builds before the commit that fixes this bug are affected. No specific version range is listed, but any kernel that does not contain the patch that removes the use‑after‑free in smc_llc_srv_add_link() is vulnerable. The CVE does not specify particular release numbers, so all current and older kernels lacking the fix are considered at risk.

Risk and Exploitability

The CVSS score of 5.2 indicates a moderate severity. The EPSS score is not available, and the vulnerability is not listed in CISA’s KEV catalog. The bug is triggered by operations within the SMC framework; the likely attack vector is local, requiring the ability to initiate an SMC LLC link with specific parameters (e.g., max_recv_sge set to 1). An attacker with local kernel privileges could trigger the fault, leading to memory corruption and possible escalation. Because the flaw is not remotely reachable through a network interface, the immediate threat is limited to trusted or compromised local contexts.

Generated by OpenCVE AI on September 12, 2026 at 03:15 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Apply the kernel patch that removes the use‑after‑free from smc_llc_srv_add_link() or upgrade the system to a kernel version that includes the commit referenced in the advisory (e.g., the commit a42a459ef0e54cb0c4b3e43e21cb0e658e664f64).
  • If upgrading or patching is not immediately possible, disable or restrict the SMC subsystem in the kernel configuration (e.g., set CONFIG_SMC=m or remove related modules) so that the vulnerable code path cannot be exercised.
  • If the SMC subsystem must remain enabled, configure the kernel to use the latest SMC implementation that excludes the vulnerable code path, or apply the specific commit that backports the fix if available from the vendor.

Generated by OpenCVE AI on September 12, 2026 at 03:15 UTC.

Tracking

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Advisories

No advisories yet.

History

Sun, 13 Sep 2026 06:45:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 5.2, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:H'}

 cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}

Sat, 12 Sep 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-825
References
Metrics threat_severity

None

 cvssV3_1

{'score': 5.2, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:H'}

threat_severity

Moderate

Fri, 11 Sep 2026 23:45:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: net/smc: fix use-after-free of the LLC qentry in smc_llc_srv_add_link() smc_llc_srv_add_link() keeps add_llc pointing into the queue entry: add_llc = &qentry->msg.add_link; smc_llc.c:1482 ... smc_llc_save_add_link_info(link_new, add_llc); smc_llc.c:1494 smc_llc_flow_qentry_del(&lgr->llc_flow_lcl); smc_llc.c:1495 ... u8 *llc_msg = smc_link_shared_v2_rxbuf(link) ? (u8 *)lgr->wr_rx_buf_v2 : (u8 *)add_llc; smc_llc.c:1504 smc_llc_save_add_link_rkeys(link, link_new, llc_msg); smc_llc.c:1506 smc_llc_flow_qentry_del() kfree()s the entry, so on a link without a shared v2 receive buffer the pointer handed to smc_llc_save_add_link_rkeys() is already freed. Before the Fixes: commit that branch always used lgr->wr_rx_buf_v2 and add_llc was not used after the free. Reproduced on an unpatched tree over rxe, with KASAN, kasan_multi_shot and a link forced to max_recv_sge == 1: the entry is freed and read by the same call, and the freeing frame is smc_llc_srv_add_link() itself. [ 2.523161] BUG: KASAN: slab-use-after-free in smc_llc_save_add_link_rkeys+0x333/0x350 [ 2.523499] Read of size 2 at addr ffff8880052194de by task kworker/0:1/11 [ 2.523789] [ 2.523862] CPU: 0 UID: 0 PID: 11 Comm: kworker/0:1 Not tainted 7.2.0-rc5-p0-g2c9dd296545d #35 PREEMPT(lazy) [ 2.523865] Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 2.523866] Workqueue: smc_hs_wq smc_listen_work [ 2.523869] Call Trace: [ 2.523870] <TASK> [ 2.523871] dump_stack_lvl+0x53/0x70 [ 2.523872] print_report+0xd0/0x630 [ 2.523874] ? __pfx__raw_spin_lock_irqsave+0x10/0x10 [ 2.523876] ? smc_llc_save_add_link_rkeys+0x333/0x350 [ 2.523878] kasan_report+0xce/0x100 [ 2.523879] ? smc_llc_save_add_link_rkeys+0x333/0x350 [ 2.523881] smc_llc_save_add_link_rkeys+0x333/0x350 [ 2.523883] ? smcr_buf_reg_lgr+0x2a4/0x660 [ 2.523885] smc_llc_srv_add_link+0xaa2/0x1e50 [ 2.523888] ? _printk+0xba/0xf0 [ 2.523897] ? __pfx_smc_llc_srv_add_link+0x10/0x10 [ 2.523899] ? down_write+0xb0/0x130 [ 2.523903] ? __pfx_down_write+0x10/0x10 [ 2.523905] smc_listen_work+0x489e/0x4d00 [ 2.523907] ? kmem_cache_free+0x1c6/0x3a0 [ 2.523911] ? __pfx_smc_listen_work+0x10/0x10 [ 2.523913] ? release_sock+0x148/0x1d0 [ 2.523915] ? smc_tcp_listen_work+0xb4f/0xfc0 [ 2.523917] ? _raw_spin_lock_irq+0x80/0xe0 [ 2.523918] ? __pfx__raw_spin_lock_irq+0x10/0x10 [ 2.523920] process_one_work+0x633/0x1030 [ 2.523922] ? assign_work+0x11d/0x370 [ 2.523924] worker_thread+0x45b/0xd10 [ 2.523926] ? __pfx_worker_thread+0x10/0x10 [ 2.523928] ? __pfx_worker_thread+0x10/0x10 [ 2.523929] kthread+0x2c6/0x3b0 [ 2.523931] ? recalc_sigpending+0x15c/0x1e0 [ 2.523934] ? __pfx_kthread+0x10/0x10 [ 2.523935] ret_from_fork+0x36e/0x5a0 [ 2.523937] ? __pfx_ret_from_fork+0x10/0x10 [ 2.523938] ? __switch_to+0x572/0xdd0 [ 2.523943] ? __pfx_kthread+0x10/0x10 [ 2.523944] ret_from_fork_asm+0x1a/0x30 [ 2.523947] </TASK> [ 2.523948] [ 2.531253] Allocated by task 48: [ 2.531399] kasan_save_stack+0x33/0x60 [ 2.531570] kasan_save_track+0x14/0x30 [ 2.531737] __kasan_kmalloc+0x8f/0xa0 [ 2.531905] __kmalloc_cache_noprof+0x158/0x370 [ 2.532100] smc_llc_enqueue+0x72/0x560 [ 2.532268] smc_wr_rx_tasklet_fn+0x474/0xa80 [ 2.532491] tasklet_action_common+0x20f/0x8a0 [ 2.532714] handle_softirqs+0x18e/0x590 [ 2.532886] do_softirq+0x3b/0x60 [ 2.533036] __local_bh_enable_ip+0x61/0x70 [ 2.533221] __alloc_skb+0x732/0x890 [ 2.533384] rxe_init_packet+0x16b/0x4f0 [ 2.533567] prepare_ack_packet+0xb8/0x830 [ 2.533760] rxe_receiver+0x495/0x96e0 [ 2.533933] do_work+0x144/0x470 [ 2 ---truncated---
Title net/smc: fix use-after-free of the LLC qentry in smc_llc_srv_add_link()
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-09-13T06:28:47.705Z

Reserved: 2026-08-26T14:34:25.811Z

Link: CVE-2026-80981

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-11T20:19:04.520

Modified: 2026-09-13T07:17:05.000

Link: CVE-2026-80981

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-09-11T19:42:41Z

Links: CVE-2026-80981 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-09-12T03:15:06Z

Weaknesses
  • CWE-825

    Expired Pointer Dereference