Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756491Ab2FNUsM (ORCPT ); Thu, 14 Jun 2012 16:48:12 -0400 Received: from mail-lpp01m010-f46.google.com ([209.85.215.46]:36070 "EHLO mail-lpp01m010-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754352Ab2FNUsL (ORCPT ); Thu, 14 Jun 2012 16:48:11 -0400 From: Marko Kohtala To: Olof Johansson , Matthew Garrett Cc: Marko Kohtala , linux-kernel@vger.kernel.org Subject: [PATCH] efivars: prevent Oops if efi_enabled but no EFI runtime Date: Thu, 14 Jun 2012 23:47:30 +0300 Message-Id: <1339706851-10618-1-git-send-email-marko.kohtala@gmail.com> X-Mailer: git-send-email 1.7.10.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2275 Lines: 69 Since v3.3-rc4-5-g1adbfa3, there has been an Oops in register_efivars calling ops->get_next_variable and ending up at EIP 0 during module init. I boot 32-bit x86 kernel from 64-bit EFI bootloader. The efi_enabled is true, but runtime is not available. The functions are NULL due to 32/64-bit mismatch between kernel and EFI. Signed-off-by: Marko Kohtala --- I currently see this on v3.4.2. I could not figure out how I'm supposed to detect lack of runtime, so I ended up with this quick and overly precise check that all required functions are available. There may be other drivers that need to take this new condition into account, so maybe Olof wants to make a better fix. drivers/firmware/efivars.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c index 47408e8..612a097 100644 --- a/drivers/firmware/efivars.c +++ b/drivers/firmware/efivars.c @@ -1223,12 +1223,16 @@ efivars_init(void) return -ENOMEM; } - ops.get_variable = efi.get_variable; - ops.set_variable = efi.set_variable; - ops.get_next_variable = efi.get_next_variable; - error = register_efivars(&__efivars, &ops, efi_kobj); - if (error) - goto err_put; + /* We may have efi_enabled for systab, but no runtime for variables. + * Check the functions we need before proceeding. */ + if (efi.get_variable && efi.set_variable && efi.get_next_variable) { + ops.get_variable = efi.get_variable; + ops.set_variable = efi.set_variable; + ops.get_next_variable = efi.get_next_variable; + error = register_efivars(&__efivars, &ops, efi_kobj); + if (error) + goto err_put; + } /* Don't forget the systab entry */ error = sysfs_create_group(efi_kobj, &efi_subsys_attr_group); @@ -1251,10 +1255,10 @@ err_put: static void __exit efivars_exit(void) { - if (efi_enabled) { + if (__efivars.kset) unregister_efivars(&__efivars); + if (efi_kobj) kobject_put(efi_kobj); - } } module_init(efivars_init); -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/