[patch 33/54] x86: fix oprofile double free

Chris Wright
2007-06-08T07:42:30Z

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-stable review patch. If anyone has any objections, please let us know.
---------------------

From: Chris Wright <chrisw@sous-sol.org>

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: Greg Kroah-Hartman <gregkh@suse.de>
---

arch/i386/oprofile/nmi_int.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

--- linux-2.6.21.4.orig/arch/i386/oprofile/nmi_int.c
+++ linux-2.6.21.4/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);

--