6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Linus Walleij <linus.walleij@xxxxxxxxxx>
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@xxxxxxxxxxxxxxx
Fixes: a1c510d0adc6 ("ARM: implement support for vmap'ed stacks")
Link: https://lore.kernel.org/linux-arm-kernel/a1a1d062-f3a2-4d05-9836-3b098de9db6d@xxxxxxxxxxx/
Reported-by: Clement LE GOFFIC <clement.legoffic@xxxxxxxxxxx>
Suggested-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Russell King (Oracle) <rmk+kernel@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm/kernel/entry-armv.S | 8 ++++++++
1 file changed, 8 insertions(+)
--- 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
