riscv: misaligned: Restrict user access to kernel memory

raw_copy_{to,from}_user() do not call access_ok(), so this code allowed
userspace to access any virtual memory address.

Cc: stable@vger.kernel.org
Fixes: 7c83232 ("riscv: add support for misaligned trap handling in S-mode")
Fixes: 4413815 ("riscv: misaligned: remove CONFIG_RISCV_M_MODE specific code")
Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20240815005714.1163136-1-samuel.holland@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Author: SiFiveHolland

arch/riscv/kernel/traps_misaligned.c

@@ -417,7 +417,7 @@ int handle_misaligned_load(struct pt_regs *regs)
 
 	val.data_u64 = 0;
 	if (user_mode(regs)) {
-		if (raw_copy_from_user(&val, (u8 __user *)addr, len))
+		if (copy_from_user(&val, (u8 __user *)addr, len))
 			return -1;
 	} else {
 		memcpy(&val, (u8 *)addr, len);
@@ -515,7 +515,7 @@ int handle_misaligned_store(struct pt_regs *regs)
 		return -EOPNOTSUPP;
 
 	if (user_mode(regs)) {
-		if (raw_copy_to_user((u8 __user *)addr, &val, len))
+		if (copy_to_user((u8 __user *)addr, &val, len))
 			return -1;
 	} else {
 		memcpy((u8 *)addr, &val, len);