riscv: Avoid enabling interrupts in die()

While working on something else, I noticed that the kernel would start
accepting interrupts again after crashing in an interrupt handler. Since
the kernel is already in inconsistent state, enabling interrupts is
dangerous and opens up risk of kernel state deteriorating further.
Interrupts do get enabled via what looks like an unintended side effect of
spin_unlock_irq, so switch to the more cautious
spin_lock_irqsave/spin_unlock_irqrestore instead.

Fixes: 76d2a0493a17 ("RISC-V: Init and Halt Code")
Signed-off-by: Mattias Nissler <mnissler@rivosinc.com>
Reviewed-by: Björn Töpel <bjorn@kernel.org>
Link: https://lore.kernel.org/r/20230215144828.3370316-1-mnissler@rivosinc.com
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
index 549bde5c970a13e9412148c7c45aca1ef2034825..70c98ce23be2454c569e1100f4e30a7fc3a5345e 100644 (file)
--- a/arch/riscv/kernel/traps.c
+++ b/arch/riscv/kernel/traps.c
@@ -34,10 +34,11 @@ void die(struct pt_regs *regs, const char *str)
        static int die_counter;
        int ret;
        long cause;
+       unsigned long flags;
 
        oops_enter();
 
-       spin_lock_irq(&die_lock);
+       spin_lock_irqsave(&die_lock, flags);
        console_verbose();
        bust_spinlocks(1);
 
@@ -54,7 +55,7 @@ void die(struct pt_regs *regs, const char *str)
 
        bust_spinlocks(0);
        add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
-       spin_unlock_irq(&die_lock);
+       spin_unlock_irqrestore(&die_lock, flags);
        oops_exit();
 
        if (in_interrupt())