Re: [PATCH 09/10] Fix efi_bind_block.

[Tom Rini <trini@konsulko.com>]

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On Tue, Dec 10, 2024 at 09:17:26AM -0700, Simon Glass wrote:
> Hi Heinrich,
> 
> On Tue, 10 Dec 2024 at 01:50, Heinrich Schuchardt <xypron.glpk@gmx.de> wrote:
> >
> > On 23.11.24 20:55, Matthew Garrett wrote:
> > > From: Janis Danisevskis <jdanisevskis@aurora.tech>
> > >
> > > efi_bind_block had two issues.
> > > 1. A pointer to a the stack was inserted as plat structure and thus used
> > > beyond its life time.
> > > 2. Only the first segment of the device path was copied into the
> > > platfom data structure resulting in an unterminated device path.
> > >
> > > Signed-off-by: Janis Danisevskis <jdanisevskis@aurora.tech>
> > > Signed-off-by: Matthew Garrett <mgarrett@aurora.tech>
> > > ---
> > >
> > >   lib/efi/efi_app_init.c | 29 +++++++++++++++++++++--------
> > >   1 file changed, 21 insertions(+), 8 deletions(-)
> > >
> > > diff --git a/lib/efi/efi_app_init.c b/lib/efi/efi_app_init.c
> > > index 9704020b749..cc91e1d74b8 100644
> > > --- a/lib/efi/efi_app_init.c
> > > +++ b/lib/efi/efi_app_init.c
> > > @@ -19,6 +19,15 @@
> > >
> > >   DECLARE_GLOBAL_DATA_PTR;
> > >
> > > +static size_t device_path_length(const struct efi_device_path *device_path)
> > > +{
> > > +     const struct efi_device_path *d;
> > > +
> > > +     for (d = device_path; d->type != DEVICE_PATH_TYPE_END; d = (void *)d + d->length) {
> > > +     }
> > > +     return (void *)d - (void *)device_path + d->length;
> > > +}
> > > +
> > >   /**
> > >    * efi_bind_block() - bind a new block device to an EFI device
> > >    *
> > > @@ -39,19 +48,23 @@ int efi_bind_block(efi_handle_t handle, struct efi_block_io *blkio,
> > >                  struct efi_device_path *device_path, int len,
> > >                  struct udevice **devp)
> > >   {
> > > -     struct efi_media_plat plat;
> > > +     struct efi_media_plat *plat;
> > >       struct udevice *dev;
> > >       char name[18];
> > >       int ret;
> > > -
> > > -     plat.handle = handle;
> > > -     plat.blkio = blkio;
> > > -     plat.device_path = malloc(device_path->length);
> > > -     if (!plat.device_path)
> > > +     size_t device_path_len = device_path_length(device_path);
> > > +
> > > +     plat = malloc(sizeof(struct efi_media_plat));
> > > +     if (!plat)
> > > +             return log_msg_ret("plat", -ENOMEM);
> > > +     plat->handle = handle;
> > > +     plat->blkio = blkio;
> > > +     plat->device_path = malloc(device_path_len);
> > > +     if (!plat->device_path)
> > >               return log_msg_ret("path", -ENOMEM);
> > > -     memcpy(plat.device_path, device_path, device_path->length);
> > > +     memcpy(plat->device_path, device_path, device_path_len);
> > >       ret = device_bind(dm_root(), DM_DRIVER_GET(efi_media), "efi_media",
> > > -                       &plat, ofnode_null(), &dev);
> > > +                       plat, ofnode_null(), &dev);
> > >       if (ret)
> > >               return log_msg_ret("bind", ret);
> >
> > Here you have a memory leak for pointer plat if ret != 0.
> >
> > Simon suggested a follow up patch. Instead we should fix it in this patch.
> >
> > @Simon
> > The logic in the caller setup_block() looks wrong.
> >
> > LocateHandle() does not ensure that when you try to read from the block
> > device the same still does exist. E.g. if a USB device is removed the
> > block IO protocol could be uninstalled and the handle deleted and the
> > EFI app may crash. Please, call OpenProtocol() with attribute BY_DRIVER.
> >
> > HandleProtocol() is considered deprecated. Please, use OpenProtocol()
> > instead.
> 
> Can you please send a follow-up with your ideas on this?

Simon, it's in your tree. The normal path here would be that the
submitter would correct this in v2. But you're trying to short-circuit
that path for your own reasons. No one should be making work on top of
your tree except for you.

-- 
Tom

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