linux-kernel - [PATCH v4 31/35] s390/traps: Unpoison the kernel_stack_overflow()'s pt

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Message-ID: <20240613153924.961511-32-iii@linux.ibm.com>
Date: Thu, 13 Jun 2024 17:34:33 +0200
From: Ilya Leoshkevich <iii@...ux.ibm.com>
To: Alexander Gordeev <agordeev@...ux.ibm.com>,
        Alexander Potapenko <glider@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Christoph Lameter <cl@...ux.com>, David Rientjes <rientjes@...gle.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>, Marco Elver <elver@...gle.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Pekka Enberg <penberg@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Vasily Gorbik <gor@...ux.ibm.com>, Vlastimil Babka <vbabka@...e.cz>
Cc: Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Hyeonggon Yoo <42.hyeyoo@...il.com>, kasan-dev@...glegroups.com,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-s390@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
        Mark Rutland <mark.rutland@....com>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Ilya Leoshkevich <iii@...ux.ibm.com>
Subject: [PATCH v4 31/35] s390/traps: Unpoison the kernel_stack_overflow()'s pt_regs

This is normally done by the generic entry code, but the
kernel_stack_overflow() flow bypasses it.

Reviewed-by: Alexander Potapenko <glider@...gle.com>
Acked-by: Heiko Carstens <hca@...ux.ibm.com>
Signed-off-by: Ilya Leoshkevich <iii@...ux.ibm.com>
---
 arch/s390/kernel/traps.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/s390/kernel/traps.c b/arch/s390/kernel/traps.c
index 52578b5cecbd..dde69d2a64f0 100644
--- a/arch/s390/kernel/traps.c
+++ b/arch/s390/kernel/traps.c
@@ -27,6 +27,7 @@
 #include <linux/uaccess.h>
 #include <linux/cpu.h>
 #include <linux/entry-common.h>
+#include <linux/kmsan.h>
 #include <asm/asm-extable.h>
 #include <asm/vtime.h>
 #include <asm/fpu.h>
@@ -262,6 +263,11 @@ static void monitor_event_exception(struct pt_regs *regs)
 
 void kernel_stack_overflow(struct pt_regs *regs)
 {
+	/*
+	 * Normally regs are unpoisoned by the generic entry code, but
+	 * kernel_stack_overflow() is a rare case that is called bypassing it.
+	 */
+	kmsan_unpoison_entry_regs(regs);
 	bust_spinlocks(1);
 	printk("Kernel stack overflow.\n");
 	show_regs(regs);
-- 
2.45.1