On 10/16/24 21:15, Linus Walleij wrote:
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>
---
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 1dfae1af8e31..12a4040a04ff 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, ip, lsr #KASAN_SHADOW_SCALE_SHIFT
Hello Linus,
While ARM TRM says that if Rd is the same of Rn then it can be omitted,
such syntax causes error on my build.
Looking around for such syntax in the kernel, this line should be :
add r2, r2, ip, lsr #KASAN_SHADOW_SCALE_SHIFT
Regards,
Clement
