CVE-2026-64103

Published Jul 19, 2026

Description

In the Linux kernel, the following vulnerability has been resolved: 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().

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References

Frequently Asked Questions

What is CVE-2026-64103? +
In the Linux kernel, the following vulnerability has been resolved: 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().
How do I check if I'm vulnerable to CVE-2026-64103? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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