aio-win32: avoid out-of-bounds access to the events array
If ret is WAIT_TIMEOUT and there was an event returned by select(),
we can write to a location after the end of the array. But in
that case we can retry the WaitForMultipleObjects call with the
same set of events, so just move the event[ret - WAIT_OBJECT_0]
assignment inside the existin conditional.
Reported-by: TeLeMan <geleman@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: TeLeMan <geleman@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
diff --git a/aio-win32.c b/aio-win32.c
index 7daeae1..d81313b 100644
--- a/aio-win32.c
+++ b/aio-win32.c
@@ -335,6 +335,7 @@
event = NULL;
if ((DWORD) (ret - WAIT_OBJECT_0) < count) {
event = events[ret - WAIT_OBJECT_0];
+ events[ret - WAIT_OBJECT_0] = events[--count];
} else if (!have_select_revents) {
break;
}
@@ -343,9 +344,6 @@
blocking = false;
progress |= aio_dispatch_handlers(ctx, event);
-
- /* Try again, but only call each handler once. */
- events[ret - WAIT_OBJECT_0] = events[--count];
}
progress |= timerlistgroup_run_timers(&ctx->tlg);