Yoshiaki Tamura <tamura.yoshiaki@xxxxxxxxxxxxx> wrote:
> Make deleting handlers robust against deletion of any elements in a
> handler by using a deleted flag like in file descriptors.
>
> Signed-off-by: Yoshiaki Tamura <tamura.yoshiaki@xxxxxxxxxxxxx>
> ---
> vl.c | 13 +++++++++----
> 1 files changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/vl.c b/vl.c
> index b436952..4e263c3 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -1158,6 +1158,7 @@ static void nographic_update(void *opaque)
> struct vm_change_state_entry {
> VMChangeStateHandler *cb;
> void *opaque;
> + int deleted;
> QLIST_ENTRY (vm_change_state_entry) entries;
> };
>
> @@ -1178,8 +1179,7 @@ VMChangeStateEntry *qemu_add_vm_change_state_handler(VMChangeStateHandler *cb,
>
> void qemu_del_vm_change_state_handler(VMChangeStateEntry *e)
> {
> - QLIST_REMOVE (e, entries);
> - qemu_free (e);
> + e->deleted = 1;
> }
>
> void vm_state_notify(int running, int reason)
> @@ -1188,8 +1188,13 @@ void vm_state_notify(int running, int reason)
>
> trace_vm_state_notify(running, reason);
>
> - for (e = vm_change_state_head.lh_first; e; e = e->entries.le_next) {
> - e->cb(e->opaque, running, reason);
this needs to become:
> + QLIST_FOREACH(e, &vm_change_state_head, entries) {
> + if (e->deleted) {
> + QLIST_REMOVE(e, entries);
> + qemu_free(e);
> + } else {
> + e->cb(e->opaque, running, reason);
> + }
VMChangeState_entry *next;
QLIST_FOREACH_SAFE(e, &vm_change_state_head, entries, next) {
.....
Otherwise you are accessing "e" after qemu_free and being put out of
the list.
Later, Juan.
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