x86: fix oprofile double free

Chuck reports that the recent fix from Andi to oprofile
6c977aad03a18019015035958c65b6729cd0574c introduces a double free.  Each
cpu's cpu_msrs is setup to point to cpu 0's, which causes free_msrs to free
cpu 0's pointers for_each_possible_cpu.  Rather than copy the pointers, do
a deep copy instead.

[acme@redhat.com: allocate_msrs() was using for_each_online_cpu()]
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Cc: Andi Kleen <ak@suse.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Dave Jones <davej@redhat.com>
Cc: Chuck Ebbert <cebbert@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/i386/oprofile/nmi_int.c b/arch/i386/oprofile/nmi_int.c
index a7c0783..11b7a51 100644 (file)
--- a/arch/i386/oprofile/nmi_int.c
+++ b/arch/i386/oprofile/nmi_int.c
@@ -154,7 +154,7 @@ static int allocate_msrs(void)
        size_t counters_size = sizeof(struct op_msr) * model->num_counters;
 
        int i;
-       for_each_online_cpu(i) {
+       for_each_possible_cpu(i) {
                cpu_msrs[i].counters = kmalloc(counters_size, GFP_KERNEL);
                if (!cpu_msrs[i].counters) {
                        success = 0;
@@ -211,8 +211,14 @@ static int nmi_setup(void)
        /* Assume saved/restored counters are the same on all CPUs */
        model->fill_in_addresses(&cpu_msrs[0]);
        for_each_possible_cpu (cpu) {
-               if (cpu != 0)
-                       cpu_msrs[cpu] = cpu_msrs[0];
+               if (cpu != 0) {
+                       memcpy(cpu_msrs[cpu].counters, cpu_msrs[0].counters,
+                               sizeof(struct op_msr) * model->num_counters);
+
+                       memcpy(cpu_msrs[cpu].controls, cpu_msrs[0].controls,
+                               sizeof(struct op_msr) * model->num_controls);
+               }
+
        }
        on_each_cpu(nmi_save_registers, NULL, 0, 1);
        on_each_cpu(nmi_cpu_setup, NULL, 0, 1);