linux-cve-announce - CVE-2023-53694: riscv: ftrace: Fixup panic by disabling preemption

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Message-ID: <2025102210-CVE-2023-53694-ed6b@gregkh>
Date: Wed, 22 Oct 2025 15:24:33 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-53694: riscv: ftrace: Fixup panic by disabling preemption

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

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

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

riscv: ftrace: Fixup panic by disabling preemption

In RISCV, we must use an AUIPC + JALR pair to encode an immediate,
forming a jump that jumps to an address over 4K. This may cause errors
if we want to enable kernel preemption and remove dependency from
patching code with stop_machine(). For example, if a task was switched
out on auipc. And, if we changed the ftrace function before it was
switched back, then it would jump to an address that has updated 11:0
bits mixing with previous XLEN:12 part.

p: patched area performed by dynamic ftrace
ftrace_prologue:
p|      REG_S   ra, -SZREG(sp)
p|      auipc   ra, 0x? ------------> preempted
					...
				change ftrace function
					...
p|      jalr    -?(ra) <------------- switched back
p|      REG_L   ra, -SZREG(sp)
func:
	xxx
	ret

The Linux kernel CVE team has assigned CVE-2023-53694 to this issue.


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

	Issue introduced in 5.12 with commit afc76b8b80112189b6f11e67e19cf58301944814 and fixed in 6.1.23 with commit 84cfcf240f4a577733b1d98fcd2611a611612b03
	Issue introduced in 5.12 with commit afc76b8b80112189b6f11e67e19cf58301944814 and fixed in 6.2.3 with commit 20a7510e781084364691b4962de31de758194cc9
	Issue introduced in 5.12 with commit afc76b8b80112189b6f11e67e19cf58301944814 and fixed in 6.3 with commit 8547649981e6631328cd64f583667501ae385531

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-2023-53694
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/Kconfig


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/84cfcf240f4a577733b1d98fcd2611a611612b03
	https://git.kernel.org/stable/c/20a7510e781084364691b4962de31de758194cc9
	https://git.kernel.org/stable/c/8547649981e6631328cd64f583667501ae385531