From: Erick Archer <erick.archer@gmx.com>
To: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Cc: Erick Archer <erick.archer@gmx.com>,
Kalle Valo <kvalo@kernel.org>,
Johannes Berg <johannes.berg@intel.com>,
Kees Cook <keescook@chromium.org>,
linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-hardening@vger.kernel.org
Subject: Re: [PATCH] mwl8k: Avoid overlapping composite structs that contain flex-arrays
Date: Sun, 17 Mar 2024 16:22:25 +0100 [thread overview]
Message-ID: <20240317152225.GA2850@titan> (raw)
In-Reply-To: <cfc4c4c0-83f8-437c-8146-6b86968db67b@embeddedor.com>
Hi Gustavo,
On Sat, Mar 16, 2024 at 12:59:11PM -0600, Gustavo A. R. Silva wrote:
>
> [..]
>
> >
> > Link: https://github.com/KSPP/linux/issues/202 [1]
> > Signed-off-by: Erick Archer <erick.archer@gmx.com>
> > ---
> > Hi everyone,
> >
> > This patch is based on my understanding of the code. Any comments would
> > be greatly appreciated.
>
> Thanks for looking into this. :)
>
> I'm currently in the process of trying a general solution for all these
> composite structures without having to use two separate structs, avoid too
> much code churn, and continue allowing for __counted_by() annotations at
> the same time.
I searched the mailing list and found several of your patches:
Link: https://lore.kernel.org/linux-hardening/ZfCXBykRw5XqBvf0@neat/
Link: https://lore.kernel.org/linux-hardening/cover.1709658886.git.gustavoars@kernel.org/
Link: https://lore.kernel.org/linux-hardening/ZeeaRuTpuxInH6ZB@neat/
In all of them you use the `struct_group_tagged()` helper to solve the
overlapping scenario. Great proposal ;)
> I'll be sending a bunch of patches once the merge window closes. So, for
> now, I think it's wise to wait for those patches.
So, are you working in a patch for the "mwl8k"? Or do you prefer
a v2 of this patch based on your proposal?
>
> More comments below.
>
> [..]
>
> > diff --git a/drivers/net/wireless/marvell/mwl8k.c b/drivers/net/wireless/marvell/mwl8k.c
> > index ce8fea76dbb2..57de32ba4efc 100644
> > --- a/drivers/net/wireless/marvell/mwl8k.c
> > +++ b/drivers/net/wireless/marvell/mwl8k.c
> > @@ -586,13 +586,17 @@ static int mwl8k_request_firmware(struct mwl8k_priv *priv, char *fw_image,
> > return 0;
> > }
> >
> > -struct mwl8k_cmd_pkt {
> > +struct mwl8k_cmd_pkt_hdr {
> > __le16 code;
> > __le16 length;
> > __u8 seq_num;
> > __u8 macid;
> > __le16 result;
> > - char payload[];
> > +} __packed;
> > +
> > +struct mwl8k_cmd_pkt {
> > + struct mwl8k_cmd_pkt_hdr header;
> > + char payload[];
> > } __packed;
>
> One of the problems with this is that `struct mwl8k_cmd_pkt` is candidate for a
> `__counted_by()` annotation:
>
> @@ -592,7 +592,7 @@ struct mwl8k_cmd_pkt {
> __u8 seq_num;
> __u8 macid;
> __le16 result;
> - char payload[];
> + char payload[] __counted_by(length);
> } __packed;
>
> and with the changes you propose, that is not possible anymore because the counter
> member must be at the same level or in an anonymous struct also at the same level
> as `payload`.
Ok, I understand the problem you raise and I agree.
Anyway, thanks for your comments.
Best regards,
Erick
> Thanks
> --
> Gustavo
>
next prev parent reply other threads:[~2024-03-17 15:22 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-16 15:07 [PATCH] mwl8k: Avoid overlapping composite structs that contain flex-arrays Erick Archer
2024-03-16 18:59 ` Gustavo A. R. Silva
2024-03-17 15:22 ` Erick Archer [this message]
2024-03-17 20:07 ` Gustavo A. R. Silva
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