From: Julius Werner <jwerner@chromium.org>
To: Kees Cook <keescook@chromium.org>
Cc: Julius Werner <jwerner@chromium.org>,
Jack Rosenthal <jrosenth@chromium.org>,
Paul Menzel <pmenzel@molgen.mpg.de>,
Guenter Roeck <groeck@chromium.org>,
Brian Norris <briannorris@chromium.org>,
Stephen Boyd <swboyd@chromium.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH] firmware: coreboot: Check size of table entry and split memcpy
Date: Fri, 6 Jan 2023 23:27:04 +0100 [thread overview]
Message-ID: <CAODwPW9bM8+V+JphjpNHS9YRmb+AXNQUi+VRjORkGZP6gY=ynA@mail.gmail.com> (raw)
In-Reply-To: <202301061234.D15CF0E627@keescook>
Yeah, exactly. Isn't that a bit simpler? (I wasn't aware of the
flexible array member in union issue, but it sounds like we have a
neat solution for that already.)
On Fri, Jan 6, 2023 at 9:35 PM Kees Cook <keescook@chromium.org> wrote:
>
> On Fri, Jan 06, 2023 at 04:03:35PM +0100, Julius Werner wrote:
> > Have you considered adding the flexible array member directly to the
> > union in struct coreboot_device instead? I think that would make this
> > a bit simpler by not having to copy header and data portion
> > separately.
>
> Are you thinking something like this?
>
>
> diff --git a/drivers/firmware/google/coreboot_table.c b/drivers/firmware/google/coreboot_table.c
> index 2652c396c423..564a3c908838 100644
> --- a/drivers/firmware/google/coreboot_table.c
> +++ b/drivers/firmware/google/coreboot_table.c
> @@ -93,14 +93,19 @@ static int coreboot_table_populate(struct device *dev, void *ptr)
> for (i = 0; i < header->table_entries; i++) {
> entry = ptr_entry;
>
> - device = kzalloc(sizeof(struct device) + entry->size, GFP_KERNEL);
> + if (entry->size < sizeof(*entry)) {
> + dev_warn(dev, "coreboot table entry too small!\n");
> + return -EINVAL;
> + }
> +
> + device = kzalloc(sizeof(device->dev) + entry->size, GFP_KERNEL);
> if (!device)
> return -ENOMEM;
>
> device->dev.parent = dev;
> device->dev.bus = &coreboot_bus_type;
> device->dev.release = coreboot_device_release;
> - memcpy(&device->entry, ptr_entry, entry->size);
> + memcpy(device->raw, entry, entry->size);
>
> switch (device->entry.tag) {
> case LB_TAG_CBMEM_ENTRY:
> diff --git a/drivers/firmware/google/coreboot_table.h b/drivers/firmware/google/coreboot_table.h
> index 37f4d335a606..d814dca33a08 100644
> --- a/drivers/firmware/google/coreboot_table.h
> +++ b/drivers/firmware/google/coreboot_table.h
> @@ -79,6 +79,7 @@ struct coreboot_device {
> struct lb_cbmem_ref cbmem_ref;
> struct lb_cbmem_entry cbmem_entry;
> struct lb_framebuffer framebuffer;
> + DECLARE_FLEX_ARRAY(u8, raw);
> };
> };
>
>
> --
> Kees Cook
prev parent reply other threads:[~2023-01-06 22:31 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-06 4:53 [PATCH] firmware: coreboot: Check size of table entry and split memcpy Kees Cook
2023-01-06 15:03 ` Julius Werner
2023-01-06 20:34 ` Kees Cook
2023-01-06 22:27 ` Julius Werner [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAODwPW9bM8+V+JphjpNHS9YRmb+AXNQUi+VRjORkGZP6gY=ynA@mail.gmail.com' \
--to=jwerner@chromium.org \
--cc=briannorris@chromium.org \
--cc=gregkh@linuxfoundation.org \
--cc=groeck@chromium.org \
--cc=jrosenth@chromium.org \
--cc=keescook@chromium.org \
--cc=linux-hardening@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=pmenzel@molgen.mpg.de \
--cc=swboyd@chromium.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).