x86/nmi: Make register_nmi_handler() more robust
authorThomas Gleixner <tglx@linutronix.de>
Sun, 15 May 2022 11:39:34 +0000 (13:39 +0200)
committerBorislav Petkov <bp@suse.de>
Tue, 17 May 2022 07:25:25 +0000 (09:25 +0200)
commita7fed5c0431dbfa707037848830f980e0f93cfb3
treef915d1b77fa76c9d4ef18b0c3f7a0164665e97dc
parent203d8919a9eda5d1bc68ac3cd7637588334c9dc1
x86/nmi: Make register_nmi_handler() more robust

register_nmi_handler() has no sanity check whether a handler has been
registered already. Such an unintended double-add leads to list corruption
and hard to diagnose problems during the next NMI handling.

Init the list head in the static NMI action struct and check it for being
empty in register_nmi_handler().

  [ bp: Fixups. ]

Reported-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/lkml/20220511234332.3654455-1-seanjc@google.com
arch/x86/include/asm/nmi.h
arch/x86/kernel/nmi.c