[PATCH] i386 cpu hotplug: don't access freed memory

i386 CPU init code accesses freed init memory when booting a newly-started
processor after CPU hotplug.  The cpu_devs array is searched to find the
vendor and it contains pointers to freed data.

Fix that by:

        1. Zeroing entries for freed vendor data after bootup.
        2. Changing Transmeta, NSC and UMC to all __init[data].
        3. Printing a warning (once only) and setting this_cpu
           to a safe default when the vendor is not found.

This does not change behavior for AMD systems.  They were broken already
but no error was reported.

Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 10 insertions, 1 deletions

diff --git a/arch/i386/kernel/cpu/common.c b/arch/i386/kernel/cpu/common.c
index 15aee26ec2b6..7eb9213734a3 100644
--- a/arch/i386/kernel/cpu/common.c
+++ b/arch/i386/kernel/cpu/common.c
@@ -44,6 +44,7 @@ static void default_init(struct cpuinfo_x86 * c)
 
 static struct cpu_dev default_cpu = {
         .c_init = default_init,
+        .c_vendor = "Unknown",
 };
 static struct cpu_dev * this_cpu = &default_cpu;
 
@@ -150,6 +151,7 @@ static void __devinit get_cpu_vendor(struct cpuinfo_x86 *c, int early)
 {
         char *v = c->x86_vendor_id;
         int i;
+        static int printed;
 
         for (i = 0; i < X86_VENDOR_NUM; i++) {
                 if (cpu_devs[i]) {
@@ -159,10 +161,17 @@ static void __devinit get_cpu_vendor(struct cpuinfo_x86 *c, int early)
                                 c->x86_vendor = i;
                                 if (!early)
                                         this_cpu = cpu_devs[i];
-                                break;
+                                return;
                         }
                 }
         }
+        if (!printed) {
+                printed++;
+                printk(KERN_ERR "CPU: Vendor unknown, using generic init.\n");
+                printk(KERN_ERR "CPU: Your system may be unstable.\n");
+        }
+        c->x86_vendor = X86_VENDOR_UNKNOWN;
+        this_cpu = &default_cpu;
 }