[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>

9 files changed, 77 insertions, 3 deletions

diff --git a/arch/i386/kernel/cpu/amd.c b/arch/i386/kernel/cpu/amd.c
index 333578a4e91..0810f81f2a0 100644
--- a/arch/i386/kernel/cpu/amd.c
+++ b/arch/i386/kernel/cpu/amd.c
@@ -282,3 +282,11 @@ int __init amd_init_cpu(void)
 }
 
 //early_arch_initcall(amd_init_cpu);
+
+static int __init amd_exit_cpu(void)
+{
+        cpu_devs[X86_VENDOR_AMD] = NULL;
+        return 0;
+}
+
+late_initcall(amd_exit_cpu);
diff --git a/arch/i386/kernel/cpu/centaur.c b/arch/i386/kernel/cpu/centaur.c
index 0dd92a23d62..f52669ecb93 100644
--- a/arch/i386/kernel/cpu/centaur.c
+++ b/arch/i386/kernel/cpu/centaur.c
@@ -470,3 +470,11 @@ int __init centaur_init_cpu(void)
 }
 
 //early_arch_initcall(centaur_init_cpu);
+
+static int __init centaur_exit_cpu(void)
+{
+        cpu_devs[X86_VENDOR_CENTAUR] = NULL;
+        return 0;
+}
+
+late_initcall(centaur_exit_cpu);
diff --git a/arch/i386/kernel/cpu/common.c b/arch/i386/kernel/cpu/common.c
index 15aee26ec2b..7eb9213734a 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;
 }
 
 
diff --git a/arch/i386/kernel/cpu/cyrix.c b/arch/i386/kernel/cpu/cyrix.c
index 75015975d03..00f2e058797 100644
--- a/arch/i386/kernel/cpu/cyrix.c
+++ b/arch/i386/kernel/cpu/cyrix.c
@@ -345,7 +345,7 @@ static void __init init_cyrix(struct cpuinfo_x86 *c)
 /*
  * Handle National Semiconductor branded processors
  */
-static void __devinit init_nsc(struct cpuinfo_x86 *c)
+static void __init init_nsc(struct cpuinfo_x86 *c)
 {
         /* There may be GX1 processors in the wild that are branded
          * NSC and not Cyrix.
@@ -444,6 +444,14 @@ int __init cyrix_init_cpu(void)
 
 //early_arch_initcall(cyrix_init_cpu);
 
+static int __init cyrix_exit_cpu(void)
+{
+        cpu_devs[X86_VENDOR_CYRIX] = NULL;
+        return 0;
+}
+
+late_initcall(cyrix_exit_cpu);
+
 static struct cpu_dev nsc_cpu_dev __initdata = {
         .c_vendor       = "NSC",
         .c_ident        = { "Geode by NSC" },
@@ -458,3 +466,11 @@ int __init nsc_init_cpu(void)
 }
 
 //early_arch_initcall(nsc_init_cpu);
+
+static int __init nsc_exit_cpu(void)
+{
+        cpu_devs[X86_VENDOR_NSC] = NULL;
+        return 0;
+}
+
+late_initcall(nsc_exit_cpu);
diff --git a/arch/i386/kernel/cpu/intel_cacheinfo.c b/arch/i386/kernel/cpu/intel_cacheinfo.c
index af591c73345..ffe58cee0c4 100644
--- a/arch/i386/kernel/cpu/intel_cacheinfo.c
+++ b/arch/i386/kernel/cpu/intel_cacheinfo.c
@@ -152,6 +152,7 @@ static int __cpuinit cpuid4_cache_lookup(int index, struct _cpuid4_info *this_le
         return 0;
 }
 
+/* will only be called once; __init is safe here */
 static int __init find_num_cache_leaves(void)
 {
         unsigned int            eax, ebx, ecx, edx;
diff --git a/arch/i386/kernel/cpu/nexgen.c b/arch/i386/kernel/cpu/nexgen.c
index 30898a260a5..ad87fa58058 100644
--- a/arch/i386/kernel/cpu/nexgen.c
+++ b/arch/i386/kernel/cpu/nexgen.c
@@ -61,3 +61,11 @@ int __init nexgen_init_cpu(void)
 }
 
 //early_arch_initcall(nexgen_init_cpu);
+
+static int __init nexgen_exit_cpu(void)
+{
+        cpu_devs[X86_VENDOR_NEXGEN] = NULL;
+        return 0;
+}
+
+late_initcall(nexgen_exit_cpu);
diff --git a/arch/i386/kernel/cpu/rise.c b/arch/i386/kernel/cpu/rise.c
index 8602425628c..d08d5a2811c 100644
--- a/arch/i386/kernel/cpu/rise.c
+++ b/arch/i386/kernel/cpu/rise.c
@@ -51,3 +51,11 @@ int __init rise_init_cpu(void)
 }
 
 //early_arch_initcall(rise_init_cpu);
+
+static int __init rise_exit_cpu(void)
+{
+        cpu_devs[X86_VENDOR_RISE] = NULL;
+        return 0;
+}
+
+late_initcall(rise_exit_cpu);
diff --git a/arch/i386/kernel/cpu/transmeta.c b/arch/i386/kernel/cpu/transmeta.c
index fc426380366..bdbeb77f4e2 100644
--- a/arch/i386/kernel/cpu/transmeta.c
+++ b/arch/i386/kernel/cpu/transmeta.c
@@ -84,7 +84,7 @@ static void __init init_transmeta(struct cpuinfo_x86 *c)
 #endif
 }
 
-static void transmeta_identify(struct cpuinfo_x86 * c)
+static void __init transmeta_identify(struct cpuinfo_x86 * c)
 {
         u32 xlvl;
         generic_identify(c);
@@ -111,3 +111,11 @@ int __init transmeta_init_cpu(void)
 }
 
 //early_arch_initcall(transmeta_init_cpu);
+
+static int __init transmeta_exit_cpu(void)
+{
+        cpu_devs[X86_VENDOR_TRANSMETA] = NULL;
+        return 0;
+}
+
+late_initcall(transmeta_exit_cpu);
diff --git a/arch/i386/kernel/cpu/umc.c b/arch/i386/kernel/cpu/umc.c
index 264fcad559d..2cd988f6dc5 100644
--- a/arch/i386/kernel/cpu/umc.c
+++ b/arch/i386/kernel/cpu/umc.c
@@ -31,3 +31,11 @@ int __init umc_init_cpu(void)
 }
 
 //early_arch_initcall(umc_init_cpu);
+
+static int __init umc_exit_cpu(void)
+{
+        cpu_devs[X86_VENDOR_UMC] = NULL;
+        return 0;
+}
+
+late_initcall(umc_exit_cpu);