CVE-2026-98357
Received Received - Intake

Use-After-Free in Linux Kernel iSER Target

Publication date: 2026-10-06

Last updated on: 2026-10-06

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: IB/isert: wait for deferred control PDU completions before releasing the connection isert_send_done() hands ISTATE_SEND_TASKMGTRSP, ISTATE_SEND_REJECT and ISTATE_SEND_TEXTRSP completions off to isert_comp_wq and returns. The work item then runs isert_completion_put() -> isert_put_cmd(), which reads isert_conn->conn and takes conn->cmd_lock. Nothing orders that work item against teardown. isert_wait_conn() queues isert_release_work, which frees isert_conn, and iscsit_close_connection() frees the iscsit_conn right after it returns, so the queued work can run against freed memory. Count the deferred control PDU completions per connection and let isert_wait_conn() wait for them before the release work is queued. ISTATE_SEND_LOGOUTRSP is deliberately not counted: that branch runs iscsit_logout_post_handler(), which ends up waiting for conn->conn_wait_comp, and that completion is only sent by iscsit_close_connection() after it has called iscsit_wait_conn(). Waiting for it here would deadlock. Its wait stays the existing isert_wait4logout(). The splat below is from a kernel with tracing printk()s and an msleep(200) injected into isert_do_control_comp() to widen the window: BUG: KASAN: slab-use-after-free in isert_put_cmd+0x53d/0x620 Read of size 8 at addr ffff8881054f1038 by task kworker/u17:1/182 CPU: 0 UID: 0 PID: 182 Comm: kworker/u17:1 Tainted: G B 7.2.0-rc5-TWIDE-gb8babf08acc7 #1 PREEMPT(lazy) Tainted: [B]=BAD_PAGE 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 Workqueue: isert_comp_wq isert_do_control_comp Call Trace: <TASK> dump_stack_lvl+0x53/0x70 print_report+0xd0/0x630 ? __pfx__raw_spin_lock_irqsave+0x10/0x10 ? _raw_spin_unlock_irqrestore+0x3e/0x70 ? isert_put_cmd+0x53d/0x620 kasan_report+0xce/0x100 ? isert_put_cmd+0x53d/0x620 isert_put_cmd+0x53d/0x620 ? isert_completion_put+0x305/0x330 ? isert_do_control_comp+0x2ef/0x310 process_one_work+0x633/0x1030 ? assign_work+0x11d/0x370 worker_thread+0x45b/0xd10 ? __pfx_worker_thread+0x10/0x10 ? __pfx_worker_thread+0x10/0x10 kthread+0x2c6/0x3b0 ? recalc_sigpending+0x15c/0x1e0 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x36e/0x5a0 ? __pfx_ret_from_fork+0x10/0x10 ? __switch_to+0x572/0xdd0 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 </TASK> Allocated by task 48: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 __kasan_kmalloc+0x8f/0xa0 __kmalloc_cache_noprof+0x158/0x370 isert_cma_handler+0x1e3/0x2ae0 cma_cm_event_handler+0x3e/0x240 cma_ib_req_handler+0x17d9/0x4490 cm_process_work+0x41/0x330 cm_work_handler+0x5727/0xc160 process_one_work+0x633/0x1030 worker_thread+0x45b/0xd10 kthread+0x2c6/0x3b0 ret_from_fork+0x36e/0x5a0 ret_from_fork_asm+0x1a/0x30 Freed by task 184: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3b/0x60 __kasan_slab_free+0x43/0x70 kfree+0x121/0x380 iscsit_close_connection+0x7cf/0x1e60 iscsit_take_action_for_connection_exit+0x1b6/0x360 iscsi_target_tx_thread+0x472/0x690 kthread+0x2c6/0x3b0 ret_from_fork+0x36e/0x5a0 ret_from_fork_asm+0x1a/0x30

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Meta Information

Published
2026-10-06
Last Modified
2026-10-06
Generated
2026-10-06
AI Q&A
2026-10-06
EPSS Evaluated
N/A
NVD
CVE-2026-98357
EUVD
EUVD-2026-93342

Affected Vendors & Products

Showing 9 associated CPEs
Vendor Product Version / Range
Linux Linux b8d26b3be8b33682cf163274ed07479a70554633
Linux Linux b8d26b3be8b33682cf163274ed07479a70554633
Linux Linux b8d26b3be8b33682cf163274ed07479a70554633
Linux Linux b8d26b3be8b33682cf163274ed07479a70554633
Linux Linux b8d26b3be8b33682cf163274ed07479a70554633
Linux Linux b8d26b3be8b33682cf163274ed07479a70554633
Linux Linux b8d26b3be8b33682cf163274ed07479a70554633
Linux Linux b8d26b3be8b33682cf163274ed07479a70554633
Linux Linux 3.10

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Exploitability

CWE
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a use-after-free vulnerability in the Linux kernel's iSER (iSCSI Extensions for RDMA) target driver. It occurs when deferred control PDU completions are processed after the connection is freed, leading to a race condition where freed memory is accessed. The issue arises because isert_send_done() offloads certain completions to a work queue without ensuring they complete before the connection is torn down.

Detection Guidance

This vulnerability is specific to the Linux kernel's iSER (iSCSI Extensions for RDMA) target implementation. Detection requires checking kernel logs for use-after-free errors related to isert_put_cmd or isert_conn structures. Monitor for kernel crashes or KASAN reports indicating slab-use-after-free in isert_put_cmd. Check if your system is running a vulnerable kernel version (7.2.0-rc5 or similar with the described issue).

Impact Analysis

This vulnerability can cause system crashes due to memory corruption, leading to denial-of-service conditions. Attackers could exploit it to execute arbitrary code with kernel privileges, potentially gaining full control over the affected system. It primarily affects systems using iSER for iSCSI over RDMA.

Mitigation Strategies

Apply the latest kernel patches that fix this issue. If using a vulnerable kernel, disable the iSER target functionality by unloading the isert module (rmmod isert) or disabling iSCSI target services. Monitor kernel security advisories for updates addressing CVE-2026-98357. Ensure your kernel is updated to a version where this issue is resolved.

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