From: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>
Date: Wed, 27 Jan 2021 12:24:56 +0000 (+0900)
Subject: x86/MSR: Filter MSR writes through X86_IOC_WRMSR_REGS ioctl too
X-Git-Tag: v5.10.25~1085
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=ad71e4decf494cc34f2b8ec6f68c8d71f1548bc3;p=platform%2Fkernel%2Flinux-rpi.git

x86/MSR: Filter MSR writes through X86_IOC_WRMSR_REGS ioctl too

[ Upstream commit 02a16aa13574c8526beadfc9ae8cc9b66315fa2d ]

Commit

  a7e1f67ed29f ("x86/msr: Filter MSR writes")

introduced a module parameter to disable writing to the MSR device file
and tainted the kernel upon writing. As MSR registers can be written by
the X86_IOC_WRMSR_REGS ioctl too, the same filtering and tainting should
be applied to the ioctl as well.

 [ bp: Massage commit message and space out statements. ]

Fixes: a7e1f67ed29f ("x86/msr: Filter MSR writes")
Signed-off-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210127122456.13939-1-misono.tomohiro@jp.fujitsu.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
index c0d4098..79f900f 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -184,6 +184,13 @@ static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg)
 		err = security_locked_down(LOCKDOWN_MSR);
 		if (err)
 			break;
+
+		err = filter_write(regs[1]);
+		if (err)
+			return err;
+
+		add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK);
+
 		err = wrmsr_safe_regs_on_cpu(cpu, regs);
 		if (err)
 			break;