CVE-2026-90173 in Linux
要約
〜によって VulDB • 2026年09月17日
Linuxカーネルにおいて、以下の脆弱性が修正されました：
smb: smbdirect: ib_free_cq()を使用して完了キューを解放する
smbdirect_connection_destroy_qp()は、ib_alloc_cq_any()を用いて送信および受信の完了キューを作成します。この関数はIB_POLL_WORKQUEUEの場合、workqueue上でib_cq_poll_work()を実行する内部の完了ハンドラを設定します。これらのCQ（Completion Queue）をib_destroy_cq()で破棄すると、poll workがキャンセルされる前にメモリが解放されてしまいます。
プロバイダが遅延して完了を投稿した場合（例：Soft-RoCE (rxe) がrdma_destroy_qp()の後にrxe_receiver()からRNRエラーを投稿する場合）、ハンドラは既に解放されたCQに対してib_cq_poll_work()を再キューイングし、その後のアクセスでrxe_req_notify_cq()においてフォールト（不正メモリアクセス）が発生します。
代わりにib_free_cq()を使用してください。この関数はCQを解放する前にcancel_work_sync()を実行してpoll workをキャンセルするため、解放されたキューに対して完了ハンドラが実行されることを防ぎます。
[ 1236.599526] ==================================================================
[ 1236.602142] BUG: KASAN: slab-use-after-free in ib_cq_poll_work+0xd0/0x1a0
[ 1236.605524] Read of size 8 at addr ffff888111865800 by task kworker/4:1H/82
[ 1236.609017]
[ 1236.609270] CPU: 4 UID: 0 PID: 82 Comm: kworker/4:1H Not tainted 7.2.0-rc3-next-20260717-virtme #110 PREEMPT(lazy)
[ 1236.609287] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014
[ 1236.609498] Workqueue: ib-comp-wq ib_cq_poll_work
[ 1236.609525] Call Trace:
[ 1236.609536] <TASK>
[ 1236.609545] __dump_stack+0x21/0x60
[ 1236.609562] dump_stack_lvl+0xc2/0x100
[ 1236.609573] print_address_description+0x77/0x200
[ 1236.609587] ? ib_cq_poll_work+0xd0/0x1a0
[ 1236.609597] print_report+0x58/0x70
[ 1236.609607] kasan_report+0x117/0x150
[ 1236.609623] ? ib_cq_poll_work+0xd0/0x1a0
[ 1236.609636] ? process_scheduled_works+0x954/0x1600
[ 1236.609650] ib_cq_poll_work+0xd0/0x1a0
[ 1236.609662] ? process_scheduled_works+0x954/0x1600
[ 1236.609674] process_scheduled_works+0xc22/0x1600
[ 1236.609698] ? __pfx_process_scheduled_works+0x10/0x10
[ 1236.609713] ? __pfx_assign_work+0x10/0x10
[ 1236.609726] ? lock_is_held_type+0x7b/0x110
[ 1236.609741] worker_thread+0x975/0xee0
[ 1236.609757] ? __pfx_do_raw_spin_lock+0x10/0x10
[ 1236.609775] ? __kthread_parkme+0x21e/0x260
[ 1236.609789] kthread+0x3a6/0x490
[ 1236.609800] ? __pfx_worker_thread+0x10/0x10
[ 1236.609809] ? __pfx_kthread+0x10/0x10
[ 1236.609820] ret_from_fork+0x55a/0xa20
[ 1236.609835] ? __pfx_ret_from_fork+0x10/0x10
[ 1236.609850] ? __pfx_kthread+0x10/0x10
[ 1236.609861] ret_from_fork_asm+0x1a/0x30
[ 1236.609880] </TASK>
[ 1236.609886]
[ 1236.661292] Allocated by task 5076:
[ 1236.662640] kasan_save_track+0x3e/0x80
[ 1236.663842] __kasan_kmalloc+0x72/0x90
[ 1236.664763] __kmalloc_noprof+0x2b0/0x5d0
[ 1236.665356] __ib_alloc_cq+0x284/0x1000
[ 1236.666573] __ib_alloc_cq_any+0x23e/0x340
[ 1236.668654] smbdirect_connection_create_qp+0x6f7/0x1070
[ 1236.669757] smbdirect_accept_connect_request+0x500/0x1ca0
[ 1236.672625] smbdirect_listen_rdma_event_handler+0x1655/0x1c50
[ 1236.673930] cma_listen_handler+0x1bf/0x260
[ 1236.674923] cma_cm_event_handler+0x128/0x380
[ 1236.676926] cma_ib_req_handler+0x2d3d/0x4de0
[ 1236.678368] cm_process_work+0xb0/0x530
[ 1236.680454] cm_queue_work_unlock+0xb1/0x230
[ 1236.681673] cm_work_handler+0x969f/0xdca0
[ 1236.682704] process_scheduled_works+0xc22/0x1600
[ 1236.683447] worker_thread+0x975/0xee0
[ 1236.685901] kthread+0x3a6/0x490
[ 1236.688164] ret_from_fork+0x55a/0xa20
[ 1236.689522] ret_from_fork_asm+0x1a/0x30
[ 1236.690073]
[ 1236.690378] Freed by task 5137:
[ 1236.692242] kasan_save_track+0x3e/0x80
[ 1236.694272] kasan_save_free_info+0x40/0x50
[ 1236.695514] __kasan_slab_free+0x3a/0x60
[ 1236.696773] kfree+0x14e/0x4e0
[ 1236.697216] ib_destroy_cq_user+0x18d/0x250
[ 1236.699817] smbdirect_connection_destroy_qp+0xf2/0x280
[ 1236.702115] smbdirect_socket_destroy_sync+0x1607/0x2720
[ 1236.704062] smbdirect_socket_release+0x140/0x280
[ 1236.705286] smb_direct_free_transpor
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