This is a note to let you know that I've just added the patch titled
x86/alternatives: Sync core before enabling interrupts
to the 5.15-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:
x86-alternatives-sync-core-before-enabling-interrupts.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 3ea1704a92967834bf0e64ca1205db4680d04048 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Date: Thu, 7 Dec 2023 20:49:24 +0100
Subject: x86/alternatives: Sync core before enabling interrupts
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
commit 3ea1704a92967834bf0e64ca1205db4680d04048 upstream.
text_poke_early() does:
local_irq_save(flags);
memcpy(addr, opcode, len);
local_irq_restore(flags);
sync_core();
That's not really correct because the synchronization should happen before
interrupts are re-enabled to ensure that a pending interrupt observes the
complete update of the opcodes.
It's not entirely clear whether the interrupt entry provides enough
serialization already, but moving the sync_core() invocation into interrupt
disabled region does no harm and is obviously correct.
Fixes: 6fffacb30349 ("x86/alternatives, jumplabel: Use text_poke_early() before mm_init()")
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxx>
Link: https://lore.kernel.org/r/ZT6narvE%2BLxX%2B7Be@xxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/alternative.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -963,8 +963,8 @@ void __init_or_module text_poke_early(vo
} else {
local_irq_save(flags);
memcpy(addr, opcode, len);
- local_irq_restore(flags);
sync_core();
+ local_irq_restore(flags);
/*
* Could also do a CLFLUSH here to speed up CPU recovery; but
Patches currently in stable-queue which might be from tglx@xxxxxxxxxxxxx are
queue-5.15/x86-alternatives-sync-core-before-enabling-interrupts.patch
