From b52a8d52c3125ec9a93106ed816582368de34426 Mon Sep 17 00:00:00 2001 From: Michael Bommarito Date: Sun, 19 Apr 2026 17:04:20 -0400 Subject: [PATCH] scsi: isci: Fix use-after-free in device removal path The ISCI completion tasklet is initialized in isci_host_alloc() (drivers/scsi/isci/init.c:496) and scheduled from both MSI-X and legacy interrupt handlers (drivers/scsi/isci/host.c:223,613). isci_host_deinit() stops the controller and waits for stop completion, but it never kills completion_tasklet before teardown continues. A top-of-function tasklet_kill() is not sufficient here: interrupts are only disabled when isci_host_stop_complete() runs, so until wait_for_stop() returns the IRQ handlers can still requeue the tasklet. The tasklet callback also re-enables interrupts after draining completions, so killing the tasklet before the source is quiesced leaves the same race open. Once wait_for_stop() returns, no further IRQ-driven scheduling can occur. Kill completion_tasklet there so teardown cannot race a queued tasklet running on a dead ihost. On remove or unload, the stale callback can otherwise dereference ihost and touch ihost->smu_registers after the host lifetime ends. A UML + KASAN analogue reproduced the failure class both with no tasklet_kill() and with tasklet_kill() placed before source quiesce, and stayed clean once the kill happened after quiescing the scheduling source. This mirrors commit f6ab594672d4 ("scsi: aic94xx: fix use-after-free in device removal path"), but ISCI needs the kill after wait_for_stop(). Fixes: 6f231dda6808 ("isci: Intel(R) C600 Series Chipset Storage Control Unit Driver") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-7 Assisted-by: Codex:gpt-5-4 Signed-off-by: Michael Bommarito Link: https://patch.msgid.link/20260419210420.2134639-1-michael.bommarito@gmail.com Signed-off-by: Martin K. Petersen --- drivers/scsi/isci/host.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/scsi/isci/host.c b/drivers/scsi/isci/host.c index 6d2f4c831df7..ff199bab5d1a 100644 --- a/drivers/scsi/isci/host.c +++ b/drivers/scsi/isci/host.c @@ -1252,6 +1252,9 @@ void isci_host_deinit(struct isci_host *ihost) wait_for_stop(ihost); + /* No further IRQ-driven scheduling can happen past wait_for_stop(). */ + tasklet_kill(&ihost->completion_tasklet); + /* phy stop is after controller stop to allow port and device to * go idle before shutting down the phys, but the expectation is * that i/o has been shut off well before we reach this