Hi Samuel,

On 15/08/2024 02:57, Samuel Holland wrote:

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: 7c83232161f6 ("riscv: add support for misaligned trap handling in S-mode") Fixes: 441381506ba7 ("riscv: misaligned: remove CONFIG_RISCV_M_MODE specific code") Signed-off-by: Samuel Holland samuel.holland@sifive.com

---

arch/riscv/kernel/traps_misaligned.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/kernel/traps_misaligned.c b/arch/riscv/kernel/traps_misaligned.c index b62d5a2f4541..1a76f99ff185 100644 --- a/arch/riscv/kernel/traps_misaligned.c +++ b/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);

We could even do the access_ok() *before* even calling handle_misaligned_load() in do_trap_load_misaligned() to back off earlier. But unless you think it is important, I'm fine with this patch, it's on my list for -fixes!

Reviewed-by: Alexandre Ghiti alexghiti@rivosinc.com

Thanks,

Alex