From c75288a4902b9ecd68c0f38bf792ce7ca2ece968 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Fri, 24 Sep 2021 01:55:27 +0000 Subject: [PATCH] riscv: fix a nasty sigreturn bug... commit 762df359aa5849e010ef04c3ed79d57588ce17d9 upstream. riscv has an equivalent of arm bug fixed by 653d48b22166 ("arm: fix really nasty sigreturn bug"); if signal gets caught by an interrupt that hits when we have the right value in a0 (-513), *and* another signal gets delivered upon sigreturn() (e.g. included into the blocked mask for the first signal and posted while the handler had been running), the syscall restart logics will see regs->cause equal to EXC_SYSCALL (we are in a syscall, after all) and a0 already restored to its original value (-513, which happens to be -ERESTARTNOINTR) and assume that we need to apply the usual syscall restart logics. Signed-off-by: Al Viro Fixes: e2c0cdfba7f6 ("RISC-V: User-facing API") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/YxJEiSq%2FCGaL6Gm9@ZenIV/ Signed-off-by: Palmer Dabbelt Signed-off-by: Greg Kroah-Hartman --- arch/riscv/kernel/signal.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/riscv/kernel/signal.c b/arch/riscv/kernel/signal.c index c2d5ecb..f8fb85d 100644 --- a/arch/riscv/kernel/signal.c +++ b/arch/riscv/kernel/signal.c @@ -121,6 +121,8 @@ SYSCALL_DEFINE0(rt_sigreturn) if (restore_altstack(&frame->uc.uc_stack)) goto badframe; + regs->cause = -1UL; + return regs->a0; badframe: -- 2.7.4