From c86d26b4b089ca294b3b7d915a7da61edb77935f Mon Sep 17 00:00:00 2001
From: Linus Walleij <linus.walleij@linaro.org>
Date: Wed, 23 Oct 2024 13:04:44 +0100
Subject: [PATCH] ARM: 9430/1: entry: Do a dummy read from VMAP shadow
commit 44e9a3bb76e5f2eecd374c8176b2c5163c8bb2e2 upstream.
When switching task, in addition to a dummy read from the new
VMAP stack, also do a dummy read from the VMAP stack's
corresponding KASAN shadow memory to sync things up in
the new MM context.
Cc: stable@vger.kernel.org
Fixes: a1c510d0adc6 ("ARM: implement support for vmap'ed stacks")
Link: https://lore.kernel.org/linux-arm-kernel/a1a1d062-f3a2-4d05-9836-3b098de9db6d@foss.st.com/
Reported-by: Clement LE GOFFIC <clement.legoffic@foss.st.com>
Suggested-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm/kernel/entry-armv.S | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 1dfae1af8e31b..ef6a657c8d130 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -25,6 +25,7 @@
#include <asm/tls.h>
#include <asm/system_info.h>
#include <asm/uaccess-asm.h>
+#include <asm/kasan_def.h>
#include "entry-header.S"
#include <asm/probes.h>
@@ -561,6 +562,13 @@ ENTRY(__switch_to)
@ entries covering the vmalloc region.
@
ldr r2, [ip]
+#ifdef CONFIG_KASAN_VMALLOC
+ @ Also dummy read from the KASAN shadow memory for the new stack if we
+ @ are using KASAN
+ mov_l r2, KASAN_SHADOW_OFFSET
+ add r2, r2, ip, lsr #KASAN_SHADOW_SCALE_SHIFT
+ ldr r2, [r2]
+#endif
#endif
@ When CONFIG_THREAD_INFO_IN_TASK=n, the update of SP itself is what
--
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