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[v4,2/5] x86: fix memory corruption in acpi_unmap_lsapic()

Message ID 1397488277-14865-3-git-send-email-imammedo@redhat.com (mailing list archive)
State Not Applicable, archived
Headers show

Commit Message

Igor Mammedov April 14, 2014, 3:11 p.m. UTC
if during CPU hotplug master CPU failed to wake up AP
it set percpu x86_cpu_to_apicid to BAD_APICID=0xFFFF for AP.

However following attempt to unplug that CPU will lead to
out of bound write access to __apicid_to_node[] which is
32768 items long on x86_64 kernel.

So drop setting x86_cpu_to_apicid to BAD_APICID in do_boot_cpu()
and allow acpi_processor_remove()->acpi_unmap_lsapic() cleanly
remove CPU.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
 arch/x86/kernel/smpboot.c |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)
diff mbox

Patch

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 6124f15..2988f69 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -859,8 +859,6 @@  static int do_boot_cpu(int apicid, int cpu, struct task_struct *idle)
 
 		/* was set by cpu_init() */
 		cpumask_clear_cpu(cpu, cpu_initialized_mask);
-
-		per_cpu(x86_cpu_to_apicid, cpu) = BAD_APICID;
 	}
 
 	/* mark "stuck" area as not stuck */