linux-cve-announce - CVE-2026-23217: riscv: trace: fix snapshot deadlock with sbi ecall

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Message-ID: <2026021800-CVE-2026-23217-f399@gregkh>
Date: Wed, 18 Feb 2026 15:22:08 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2026-23217: riscv: trace: fix snapshot deadlock with sbi ecall

From: Greg Kroah-Hartman <gregkh@...nel.org>

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

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

riscv: trace: fix snapshot deadlock with sbi ecall

If sbi_ecall.c's functions are traceable,

echo "__sbi_ecall:snapshot" > /sys/kernel/tracing/set_ftrace_filter

may get the kernel into a deadlock.

(Functions in sbi_ecall.c are excluded from tracing if
CONFIG_RISCV_ALTERNATIVE_EARLY is set.)

__sbi_ecall triggers a snapshot of the ringbuffer. The snapshot code
raises an IPI interrupt, which results in another call to __sbi_ecall
and another snapshot...

All it takes to get into this endless loop is one initial __sbi_ecall.
On RISC-V systems without SSTC extension, the clock events in
timer-riscv.c issue periodic sbi ecalls, making the problem easy to
trigger.

Always exclude the sbi_ecall.c functions from tracing to fix the
potential deadlock.

sbi ecalls can easiliy be logged via trace events, excluding ecall
functions from function tracing is not a big limitation.

The Linux kernel CVE team has assigned CVE-2026-23217 to this issue.

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

	Fixed in 6.18.10 with commit b1f8285bc8e3508c1fde23b5205f1270215d4984
	Fixed in 6.19 with commit b0d7f5f0c9f05f1b6d4ee7110f15bef9c11f9df0

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-2026-23217
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:
	arch/riscv/kernel/Makefile

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/b1f8285bc8e3508c1fde23b5205f1270215d4984
	https://git.kernel.org/stable/c/b0d7f5f0c9f05f1b6d4ee7110f15bef9c11f9df0