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.cordova@canonical.com --- Changes in v3: initialize ret variable in efi_net_set_dp 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(-)
diff --git a/lib/efi_loader/efi_net.c b/lib/efi_loader/efi_net.c index 67593ef50c0..f696a47060c 100644 --- a/lib/efi_loader/efi_net.c +++ b/lib/efi_loader/efi_net.c @@ -925,12 +925,15 @@ 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) @@ -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 = 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; }
/**