riscv: define ILLEGAL_POINTER_VALUE for 64bit

commit 5c178472af247c7b50f962495bb7462ba453b9fb upstream.

This is used in poison.h for poison pointer offset. Based on current
SV39, SV48 and SV57 vm layout, 0xdead000000000000 is a proper value
that is not mappable, this can avoid potentially turning an oops to
an expolit.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Fixes: fbe934d69eb7 ("RISC-V: Build Infrastructure")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240705170210.3236-1-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 006232b67b467d4004af10e19cd30caf70b8abf5..140ff98a6efff85af5ac1f54a0c89caf0fa079ca 100644 (file)
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -312,6 +312,11 @@ config GENERIC_HWEIGHT
 config FIX_EARLYCON_MEM
        def_bool MMU
 
+config ILLEGAL_POINTER_VALUE
+       hex
+       default 0 if 32BIT
+       default 0xdead000000000000 if 64BIT
+
 config PGTABLE_LEVELS
        int
        default 5 if 64BIT