From: "Gustavo A. R. Silva" <gustavoars@kernel.org>
To: Jeff Johnson <quic_jjohnson@quicinc.com>
Cc: linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org,
Kalle Valo <kvalo@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
netdev@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH 4/6][next] ath6kl: wmi: Replace one-element array with flexible-array member in struct wmi_connect_event
Date: Thu, 24 Feb 2022 14:08:39 -0600 [thread overview]
Message-ID: <20220224200839.GA1292927@embeddedor> (raw)
In-Reply-To: <6106494b-a1b3-6b57-8b44-b9528127533b@quicinc.com>
On Wed, Feb 23, 2022 at 04:50:18PM -0800, Jeff Johnson wrote:
> On 2/22/2022 6:38 PM, Gustavo A. R. Silva wrote:
> > Replace one-element array with flexible-array member in struct
> > wmi_connect_event.
> >
> > It's also worth noting that due to the flexible array transformation,
> > the size of struct wmi_connect_event changed (now the size is 1 byte
> > smaller), and in order to preserve the logic of before the transformation,
> > the following change is needed:
> >
> > - if (len < sizeof(struct wmi_connect_event))
> > + if (len <= sizeof(struct wmi_connect_event))
> >
> > This issue was found with the help of Coccinelle and audited and fixed,
> > manually.
> >
> > Link: https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays
> > Link: https://github.com/KSPP/linux/issues/79
> > Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
> > ---
> > Hi!
> >
> > It'd be great if someone can confirm or comment on the following
> > changes described in the changelog text:
> >
> > - if (len < sizeof(struct wmi_connect_event))
> > + if (len <= sizeof(struct wmi_connect_event))
> >
> > Thanks
> >
> > drivers/net/wireless/ath/ath6kl/wmi.c | 2 +-
> > drivers/net/wireless/ath/ath6kl/wmi.h | 2 +-
> > 2 files changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/wireless/ath/ath6kl/wmi.c b/drivers/net/wireless/ath/ath6kl/wmi.c
> > index 049d75f31f3c..ccdccead688e 100644
> > --- a/drivers/net/wireless/ath/ath6kl/wmi.c
> > +++ b/drivers/net/wireless/ath/ath6kl/wmi.c
> > @@ -857,7 +857,7 @@ static int ath6kl_wmi_connect_event_rx(struct wmi *wmi, u8 *datap, int len,
> > struct wmi_connect_event *ev;
> > u8 *pie, *peie;
> > - if (len < sizeof(struct wmi_connect_event))
> > + if (len <= sizeof(struct wmi_connect_event))
>
> this is another case where IMO the original code can remain since all it is
> really checking is to see if the entire "fixed" portion is present. in
> reality if there was just one byte of assoc_info the response would actually
> be invalid.
I see; that's actually what I needed to be clarified. I wasn't sure if
a channel list with no channels was valid and expected. Now I see it is. :)
> what is missing is logic that verifies len is large enough to hold the
> payload that is advertised via the beacon_ie_len, assoc_req_len, &
> assoc_resp_len members. without this even if you change the initial len
> check you can have a condition where len says there is one u8 in assoc_info
> (and pass the initial test) but the other three members indicate that much
> more data is present.
>
> but that is a pre-existing shortcoming that should be handled with a
> separate patch.
Yeah; I'll consider extending this series to include a patch for that.
> > return -EINVAL;
> > ev = (struct wmi_connect_event *) datap;
> > diff --git a/drivers/net/wireless/ath/ath6kl/wmi.h b/drivers/net/wireless/ath/ath6kl/wmi.h
> > index 432e4f428a4a..6b064e669d87 100644
> > --- a/drivers/net/wireless/ath/ath6kl/wmi.h
> > +++ b/drivers/net/wireless/ath/ath6kl/wmi.h
> > @@ -1545,7 +1545,7 @@ struct wmi_connect_event {
> > u8 beacon_ie_len;
> > u8 assoc_req_len;
> > u8 assoc_resp_len;
> > - u8 assoc_info[1];
> > + u8 assoc_info[];
> > } __packed;
> > /* Disconnect Event */
>
> whether or not you modify the length check consider this:
> Reviewed-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Great. :)
Thanks a lot for the feedback!
--
Gustavo
next prev parent reply other threads:[~2022-02-24 20:00 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-23 2:38 [PATCH 0/6][next] ath6kl: wmi: Replace one-element arrays with flexible-array members Gustavo A. R. Silva
2022-02-23 2:38 ` [PATCH 1/6][next] ath6kl: wmi: Replace one-element array with flexible-array member in struct wmi_begin_scan_cmd Gustavo A. R. Silva
2022-02-24 0:48 ` Jeff Johnson
2022-02-23 2:38 ` [PATCH 2/6][next] ath6kl: wmi: Replace one-element array with flexible-array member in struct wmi_start_scan_cmd Gustavo A. R. Silva
2022-02-23 2:38 ` [PATCH 3/6][next] ath6kl: wmi: Replace one-element array with flexible-array member in struct wmi_channel_list_reply Gustavo A. R. Silva
2022-02-24 0:49 ` Jeff Johnson
2022-02-23 2:38 ` [PATCH 4/6][next] ath6kl: wmi: Replace one-element array with flexible-array member in struct wmi_connect_event Gustavo A. R. Silva
2022-02-24 0:50 ` Jeff Johnson
2022-02-24 20:08 ` Gustavo A. R. Silva [this message]
2022-02-23 2:39 ` [PATCH 5/6][next] ath6kl: wmi: Replace one-element array with flexible-array member in struct wmi_disconnect_event Gustavo A. R. Silva
2022-02-24 0:53 ` Jeff Johnson
2022-02-23 2:39 ` [PATCH 6/6][next] ath6kl: wmi: Replace one-element array with flexible-array member in struct wmi_aplist_event Gustavo A. R. Silva
2022-02-24 1:01 ` Jeff Johnson
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