Re: [Qemu-devel] [PATCH V2] net/colo-compare.c: Fix memory leak and code style issue.

[Zhang, Chen]

> -----Original Message-----
> From: Jason Wang [mailto:address@hidden]
> Sent: Tuesday, July 9, 2019 10:48 PM
> To: Zhang, Chen <address@hidden>; Li Zhijian <address@hidden>;
> Peter Maydell <address@hidden>; qemu-dev <qemu-
> address@hidden>
> Cc: Zhang Chen <address@hidden>
> Subject: Re: [Qemu-devel] [PATCH V2] net/colo-compare.c: Fix memory leak
> and code style issue.
> 
> 
> On 2019/7/4 下午4:36, Zhang Chen wrote:
> > From: Zhang Chen <address@hidden>
> >
> > This patch to fix the origin "char *data" menory leak, code style
> > issue and add necessary check here.
> > Reported-by: Coverity (CID 1402785)
> >
> > Signed-off-by: Zhang Chen <address@hidden>
> > ---
> >   net/colo-compare.c | 28 +++++++++++++++++++++-------
> >   1 file changed, 21 insertions(+), 7 deletions(-)
> >
> > diff --git a/net/colo-compare.c b/net/colo-compare.c index
> > 909dd6c6eb..ed349f5f6a 100644
> > --- a/net/colo-compare.c
> > +++ b/net/colo-compare.c
> > @@ -127,6 +127,17 @@ static int compare_chr_send(CompareState *s,
> >                               uint32_t vnet_hdr_len,
> >                               bool notify_remote_frame);
> >
> > +static bool packet_matches_str(const char *str,
> > +                               uint8_t *buf,
> > +                               uint32_t packet_len) {
> > +    if (packet_len <= strlen(str)) {
> > +        return false;
> > +    }
> > +
> > +    return !memcmp(str, buf, strlen(str) + 1);
> 
> 
> This assumes buf is NULL terminated (you pass notify_rs->buf) which is not
> correct I think?

Yes, you are right.
How about this:

static bool packet_matches_str(const char *str,
                               uint8_t *buf,
                               uint32_t packet_len) {
    if (packet_len != strlen(str) || !buf) {
        return false;
    }

    return !memcmp(str, buf, strlen(str));
}

Thanks
Zhang Chen


> 
> Thanks
> 
> 
> > +}
> > +
> >   static void notify_remote_frame(CompareState *s)
> >   {
> >       char msg[] = "DO_CHECKPOINT";
> > @@ -1008,21 +1019,24 @@ static void
> compare_notify_rs_finalize(SocketReadState *notify_rs)
> >   {
> >       CompareState *s = container_of(notify_rs, CompareState,
> > notify_rs);
> >
> > -    /* Get Xen colo-frame's notify and handle the message */
> > -    char *data = g_memdup(notify_rs->buf, notify_rs->packet_len);
> > -    char msg[] = "COLO_COMPARE_GET_XEN_INIT";
> > +    const char msg[] = "COLO_COMPARE_GET_XEN_INIT";
> >       int ret;
> >
> > -    if (!strcmp(data, "COLO_USERSPACE_PROXY_INIT")) {
> > +    if (packet_matches_str("COLO_USERSPACE_PROXY_INIT",
> > +                           notify_rs->buf,
> > +                           notify_rs->packet_len)) {
> >           ret = compare_chr_send(s, (uint8_t *)msg, strlen(msg), 0, true);
> >           if (ret < 0) {
> >               error_report("Notify Xen COLO-frame INIT failed");
> >           }
> > -    }
> > -
> > -    if (!strcmp(data, "COLO_CHECKPOINT")) {
> > +    } else if (packet_matches_str("COLO_CHECKPOINT",
> > +                                  notify_rs->buf,
> > +                                  notify_rs->packet_len)) {
> >           /* colo-compare do checkpoint, flush pri packet and remove sec 
> > packet
> */
> >           g_queue_foreach(&s->conn_list, colo_flush_packets, s);
> > +    } else {
> > +        error_report("COLO compare got unsupported instruction '%s'",
> > +                     (char *)notify_rs->buf);
> >       }
> >   }
> >