efi_loader: efi_net: let efi_net_set_dp properly update the device path

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: e55a4acb54 ("efi_loader: net: set EFI bootdevice device path to HTTP when loaded from wget")
Signed-off-by: Adriano Cordova <adriano.cordova@canonical.com>
This commit is contained in:
Adriano Cordova 2025-01-27 09:34:45 -03:00 committed by Heinrich Schuchardt
parent 743c15b9fd
commit 2eda179568

View file

@ -927,12 +927,15 @@ efi_status_t efi_net_register(void)
&netobj->net);
if (r != EFI_SUCCESS)
goto failure_to_add_protocol;
if (!net_dp)
efi_net_set_dp("Net", NULL);
r = efi_add_protocol(&netobj->header, &efi_guid_device_path,
net_dp);
if (net_dp)
r = efi_add_protocol(&netobj->header, &efi_guid_device_path,
net_dp);
else
r = efi_net_set_dp("Net", NULL);
if (r != EFI_SUCCESS)
goto failure_to_add_protocol;
r = efi_add_protocol(&netobj->header, &efi_pxe_base_code_protocol_guid,
&netobj->pxe);
if (r != EFI_SUCCESS)
@ -1057,18 +1060,58 @@ 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 = EFI_SUCCESS;
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;
}
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;
efi_free_pool(old_net_dp);
return ret;
error:
// Failed, restore
efi_free_pool(new_net_dp);
return ret;
}
/**