Patch "riscv: Avoid enabling interrupts in die()" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    riscv: Avoid enabling interrupts in die()

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     riscv-avoid-enabling-interrupts-in-die.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 6b95ce051d8be5637ece3e3f58e8035c8b2309cf
Author: Mattias Nissler <mnissler@xxxxxxxxxxxx>
Date:   Wed Feb 15 14:48:28 2023 +0000

    riscv: Avoid enabling interrupts in die()
    
    [ Upstream commit 130aee3fd9981297ff9354e5d5609cd59aafbbea ]
    
    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@xxxxxxxxxxxx>
    Reviewed-by: Björn Töpel <bjorn@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20230215144828.3370316-1-mnissler@xxxxxxxxxxxx
    Cc: stable@xxxxxxxxxxxxxxx
    Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
    Stable-dep-of: 6a97f4118ac0 ("riscv: Fix sleeping in invalid context in die()")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
index 533087439e80..d255d88cf522 100644
--- a/arch/riscv/kernel/traps.c
+++ b/arch/riscv/kernel/traps.c
@@ -30,10 +30,11 @@ 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);
 
@@ -50,7 +51,7 @@ 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())