Re: [PATCH 2/2] util/aio-win32: Correct the event array size in aio_poll()

[Bin Meng]

On Fri, Aug 5, 2022 at 11:09 PM Stefan Weil <sw@weilnetz.de> wrote:
>
> Am 05.08.22 um 16:56 schrieb Bin Meng:
>
> > From: Bin Meng <bin.meng@windriver.com>
> >
> > WaitForMultipleObjects() can only wait for MAXIMUM_WAIT_OBJECTS
> > object handles. Correct the event array size in aio_poll() and
> > add a assert() to ensure it does not cause out of bound access.
> >
> > Signed-off-by: Bin Meng <bin.meng@windriver.com>
> > ---
> >
> >   util/aio-win32.c | 3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/util/aio-win32.c b/util/aio-win32.c
> > index 44003d645e..8cf5779567 100644
> > --- a/util/aio-win32.c
> > +++ b/util/aio-win32.c
> > @@ -326,7 +326,7 @@ void aio_dispatch(AioContext *ctx)
> >   bool aio_poll(AioContext *ctx, bool blocking)
> >   {
> >       AioHandler *node;
> > -    HANDLE events[MAXIMUM_WAIT_OBJECTS + 1];
> > +    HANDLE events[MAXIMUM_WAIT_OBJECTS];
> >       bool progress, have_select_revents, first;
> >       int count;
> >       int timeout;
> > @@ -369,6 +369,7 @@ bool aio_poll(AioContext *ctx, bool blocking)
> >       QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) {
> >           if (!node->deleted && node->io_notify
> >               && aio_node_check(ctx, node->is_external)) {
> > +            assert(count < MAXIMUM_WAIT_OBJECTS);
>
>
> Would using g_assert for new code be better? Currently the rest of that
> file (and most QEMU code) uses assert.

Yeah, I noticed that but didn't do that because I feel it's better to
be consistent, at least in this single file.

Changing to g_assert() could be a future patch, if necessary.

>
> count could also be changed from int to unsigned (which matches better
> to the unsigned DWORD).
>

changed in v2.

> Reviewed-by: Stefan Weil <sw@weilnetz.de>

Thanks!

Regards,
Bin