CVE-2026-98357

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