On 02/03/2021 07:28, Tiezhu Yang wrote:
copy_to_user() returns the amount left to copy, it should return -EFAULT
if copy to user failed.
This looks technically correct, but the caller (only one)
will check for non-zero and will covert that to -EFAULT
in setup_rt_frame().
I expect if this change is done, it also needs to be done
for the callers too and there's a few others than assume
!=0 is an error.
I think it would be easier to define save_fp_state() to
return non-zero on error and note it does not return an
error code. It may be worth exiting the functio nif
the first __copy_to_user fails?
Note: setup_rt_frame -> setup_sigcontext -> save_fp_frame
Signed-off-by: Tiezhu Yang <yangtie...@loongson.cn>
---
arch/riscv/kernel/signal.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/riscv/kernel/signal.c b/arch/riscv/kernel/signal.c
index 65942b3..2238fc5 100644
--- a/arch/riscv/kernel/signal.c
+++ b/arch/riscv/kernel/signal.c
@@ -67,7 +67,7 @@ static long save_fp_state(struct pt_regs *regs,
fstate_save(current, regs);
err = __copy_to_user(state, ¤t->thread.fstate, sizeof(*state));
if (unlikely(err))
- return err;
+ return -EFAULT;
/* We support no other extension state at this time. */
for (i = 0; i < ARRAY_SIZE(sc_fpregs->q.reserved); i++) {
@@ -140,8 +140,12 @@ static long setup_sigcontext(struct rt_sigframe __user
*frame,
{
struct sigcontext __user *sc = &frame->uc.uc_mcontext;
long err;
+
/* sc_regs is structured the same as the start of pt_regs */
err = __copy_to_user(&sc->sc_regs, regs, sizeof(sc->sc_regs));
+ if (unlikely(err))
+ return -EFAULT;
+
/* Save the floating-point state. */
if (has_fpu)
err |= save_fp_state(regs, &sc->sc_fpregs);
--
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