CVE-2026-68396: scsi: core: wake eh reliably when using scsi_schedule_eh

From: Greg Kroah-Hartman <[email protected]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

scsi: core: wake eh reliably when using scsi_schedule_eh

Drivers which use the scsi_schedule_eh function to run the error handler
currently risk the error handler thread never waking once all commands are
timed out or inactive. There is no enforced memory order between setting
the host into error recovery state and counting busy commands. This can
result in a race with scsi_dec_host_busy where neither CPU sees both
conditions of all commands inactive and the host error state to request
waking the error handler.

To fix this, run the scsi_schedule_eh's scsi_eh_wakeup from a new work item
which will use rcu to ensure scsi_schedule_eh's call to scsi_host_busy will
occur after the error state is globally visible and will be seen by any
current scsi_dec_host_busy callers.

The Linux kernel CVE team has assigned CVE-2026-68396 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.5 with commit 6eb045e092efefafc6687409a6fa6d1dabf0fb69 and fixed in 6.12.101 with commit 866efe8ae8b8b4d095501001b026e1022734be28
	Issue introduced in 5.5 with commit 6eb045e092efefafc6687409a6fa6d1dabf0fb69 and fixed in 6.18.42 with commit c7a15091237205770bd9bd4d14eb1f3029d97a34
	Issue introduced in 5.5 with commit 6eb045e092efefafc6687409a6fa6d1dabf0fb69 and fixed in 7.1.6 with commit 24d7abda6a2a19e113334accc10029f6a4b57257
	Issue introduced in 5.5 with commit 6eb045e092efefafc6687409a6fa6d1dabf0fb69 and fixed in 7.2-rc4 with commit dccf3b1798b70f94e958b3d00b83010399e6fb05

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-68396
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/scsi/hosts.c
	drivers/scsi/scsi_error.c
	drivers/scsi/scsi_priv.h
	include/scsi/scsi_host.h


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/866efe8ae8b8b4d095501001b026e1022734be28
	https://git.kernel.org/stable/c/c7a15091237205770bd9bd4d14eb1f3029d97a34
	https://git.kernel.org/stable/c/24d7abda6a2a19e113334accc10029f6a4b57257
	https://git.kernel.org/stable/c/dccf3b1798b70f94e958b3d00b83010399e6fb05