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[Qemu-devel] [PATCH] exec: Stop using memory after free
From: |
Don Slutz |
Subject: |
[Qemu-devel] [PATCH] exec: Stop using memory after free |
Date: |
Mon, 30 Nov 2015 17:11:04 -0500 |
memory_region_unref(mr) can free memory.
For example I got:
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7f43280d4700 (LWP 4462)]
0x00007f43323283c0 in phys_section_destroy (mr=0x7f43259468b0)
at /home/don/xen/tools/qemu-xen-dir/exec.c:1023
1023 if (mr->subpage) {
(gdb) bt
at /home/don/xen/tools/qemu-xen-dir/exec.c:1023
at /home/don/xen/tools/qemu-xen-dir/exec.c:1034
at /home/don/xen/tools/qemu-xen-dir/exec.c:2205
(gdb) p mr
$1 = (MemoryRegion *) 0x7f43259468b0
And this change prevents this.
Signed-off-by: Don Slutz <address@hidden>
---
exec.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/exec.c b/exec.c
index de1cf19..0bf0a6e 100644
--- a/exec.c
+++ b/exec.c
@@ -1064,9 +1064,11 @@ static uint16_t phys_section_add(PhysPageMap *map,
static void phys_section_destroy(MemoryRegion *mr)
{
+ bool have_sub_page = mr->subpage;
+
memory_region_unref(mr);
- if (mr->subpage) {
+ if (have_sub_page) {
subpage_t *subpage = container_of(mr, subpage_t, iomem);
object_unref(OBJECT(&subpage->iomem));
g_free(subpage);
--
1.8.3.1
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