On Sat, Jan 04, 2025 at 12:05:24AM +0100, Heinrich Schuchardt wrote:
> On 06.12.24 18:18, Adriano Cordova wrote:
> > This commit fixes an use after free introduced in Commit e55a4acb54
> > (" efi_loader: net: set EFI bootdevice device path to HTTP when loaded
> > from wget"). The logic in efi_net_set_dp is reworked so that when the
> > function is invoked it not only changes the value of the static variable
> > net_dp (this is how the function was implemented in e55a4acb54) but also
> > updates the protocol interface of the device path protocol in case efi
> > has started.
> >
> > Fixes: e55a4acb54e8 ("efi_loader: net: set EFI bootdevice device path to
> > HTTP when loaded from wget")
> > Signed-off-by: Adriano Cordova <adriano.cord...@canonical.com>
> > ---
> > Changes in v2: use reinstall_protocol_interface() and new_net_dp in the
> > body of efi_net_set_dp()
> >
> > lib/efi_loader/efi_net.c | 61 ++++++++++++++++++++++++++++++++++------
> > 1 file changed, 52 insertions(+), 9 deletions(-)
[snip]
> > @@ -1055,18 +1058,58 @@ out_of_resources:
> > */
> > efi_status_t efi_net_set_dp(const char *dev, const char *server)
> > {
> > - efi_free_pool(net_dp);
> > + efi_status_t ret;
> > + struct efi_handler *phandler;
> > + struct efi_device_path *old_net_dp, *new_net_dp;
> >
> > - net_dp = NULL;
> > + old_net_dp = net_dp;
> > + new_net_dp = NULL;
> > if (!strcmp(dev, "Net"))
> > - net_dp = efi_dp_from_eth();
> > + new_net_dp = efi_dp_from_eth();
> > else if (!strcmp(dev, "Http"))
> > - net_dp = efi_dp_from_http(server);
> > + new_net_dp = efi_dp_from_http(server);
> >
> > - if (!net_dp)
> > + if (!new_net_dp) {
> > return EFI_OUT_OF_RESOURCES;
> > + }
> > +
> > + // If netobj is not started yet, end here.
> > + if (!netobj) {
> > + goto exit;
>
> This leads to a build failure with clang as you have not initialized
> variable ret.
>
> https://source.denx.de/u-boot/custodians/u-boot-efi/-/jobs/987832
>
> > + }
> > +
> > + phandler = NULL;
> > + efi_search_protocol(&netobj->header, &efi_guid_device_path, &phandler);
> > +
> > + // If the device path protocol is not yet installed, install it
> > + if (!phandler)
> > + goto add;
> > +
> > + // If it is already installed, try to update it
> > + ret = efi_reinstall_protocol_interface(&netobj->header,
> > &efi_guid_device_path,
> > + old_net_dp, new_net_dp);
> > + if (ret != EFI_SUCCESS)
> > + goto error;
> > +
> > + net_dp = new_net_dp;
> > + efi_free_pool(old_net_dp);
> >
> > return EFI_SUCCESS;
> > +add:
> > + ret = efi_add_protocol(&netobj->header, &efi_guid_device_path,
> > + new_net_dp);
> > + if (ret != EFI_SUCCESS)
> > + goto error;
> > +exit:
> > + net_dp = new_net_dp;
>
> Why should we set net_dp if there is no net_obj?Because prior to this patch we set net_dp = NULL at the start of the function and with this patch nothing is updating net_dp until much later in the function. > Instead of jumping to exit, we can jump to error: with > > ret = EFI_DEVICE_ERROR. I'm not entirely sure what you mean by that. But can you perhaps v3 this? I still can't re-enable CONFIG_CMD_BOOTEFI_SELFTEST on any of my platforms due to this problem. -- Tom
signature.asc
Description: PGP signature
