From 55b4e80b047300e1512df02887b7448ba3786b62 Mon Sep 17 00:00:00 2001 From: Don Slutz Date: Mon, 30 Nov 2015 17:11:04 -0500 Subject: exec: Stop using memory after free 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 Message-Id: <1448921464-21845-1-git-send-email-Don.Slutz@Gmail.com> Cc: qemu-stable@nongnu.org Signed-off-by: Paolo Bonzini --- exec.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'exec.c') diff --git a/exec.c b/exec.c index de1cf19154..0bf0a6e7eb 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); -- cgit v1.2.1