From patchwork Mon Apr 8 09:50:53 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis Henriques X-Patchwork-Id: 234718 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id C66DB2C00F1 for ; Mon, 8 Apr 2013 19:53:09 +1000 (EST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1UP8l7-0007ci-6W; Mon, 08 Apr 2013 09:53:05 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1UP8ky-0007Nb-MN for kernel-team@lists.ubuntu.com; Mon, 08 Apr 2013 09:52:56 +0000 Received: from bl15-144-85.dsl.telepac.pt ([188.80.144.85] helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1UP8kx-00065j-V0; Mon, 08 Apr 2013 09:52:56 +0000 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 098/102] efivars: Handle duplicate names from get_next_variable() Date: Mon, 8 Apr 2013 10:50:53 +0100 Message-Id: <1365414657-29191-99-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1365414657-29191-1-git-send-email-luis.henriques@canonical.com> References: <1365414657-29191-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.5 Cc: Seiji Aguchi , Matt Fleming , Lingzhu Xiang X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 3.5.7.10 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Matt Fleming commit e971318bbed610e28bb3fde9d548e6aaf0a6b02e upstream. Some firmware exhibits a bug where the same VariableName and VendorGuid values are returned on multiple invocations of GetNextVariableName(). See, https://bugzilla.kernel.org/show_bug.cgi?id=47631 As a consequence of such a bug, Andre reports hitting the following WARN_ON() in the sysfs code after updating the BIOS on his, "Gigabyte Technology Co., Ltd. To be filled by O.E.M./Z77X-UD3H, BIOS F19e 11/21/2012)" machine, [ 0.581554] EFI Variables Facility v0.08 2004-May-17 [ 0.584914] ------------[ cut here ]------------ [ 0.585639] WARNING: at /home/andre/linux/fs/sysfs/dir.c:536 sysfs_add_one+0xd4/0x100() [ 0.586381] Hardware name: To be filled by O.E.M. [ 0.587123] sysfs: cannot create duplicate filename '/firmware/efi/vars/SbAslBufferPtrVar-01f33c25-764d-43ea-aeea-6b5a41f3f3e8' [ 0.588694] Modules linked in: [ 0.589484] Pid: 1, comm: swapper/0 Not tainted 3.8.0+ #7 [ 0.590280] Call Trace: [ 0.591066] [] ? sysfs_add_one+0xd4/0x100 [ 0.591861] [] warn_slowpath_common+0x7f/0xc0 [ 0.592650] [] warn_slowpath_fmt+0x4c/0x50 [ 0.593429] [] ? strlcat+0x65/0x80 [ 0.594203] [] sysfs_add_one+0xd4/0x100 [ 0.594979] [] create_dir+0x78/0xd0 [ 0.595753] [] sysfs_create_dir+0x86/0xe0 [ 0.596532] [] kobject_add_internal+0x9c/0x220 [ 0.597310] [] kobject_init_and_add+0x67/0x90 [ 0.598083] [] ? efivar_create_sysfs_entry+0x61/0x1c0 [ 0.598859] [] efivar_create_sysfs_entry+0x11b/0x1c0 [ 0.599631] [] register_efivars+0xde/0x420 [ 0.600395] [] ? edd_init+0x2f5/0x2f5 [ 0.601150] [] efivars_init+0xb8/0x104 [ 0.601903] [] do_one_initcall+0x12a/0x180 [ 0.602659] [] kernel_init_freeable+0x13e/0x1c6 [ 0.603418] [] ? loglevel+0x31/0x31 [ 0.604183] [] ? rest_init+0x80/0x80 [ 0.604936] [] kernel_init+0xe/0xf0 [ 0.605681] [] ret_from_fork+0x7c/0xb0 [ 0.606414] [] ? rest_init+0x80/0x80 [ 0.607143] ---[ end trace 1609741ab737eb29 ]--- There's not much we can do to work around and keep traversing the variable list once we hit this firmware bug. Our only solution is to terminate the loop because, as Lingzhu reports, some machines get stuck when they encounter duplicate names, > I had an IBM System x3100 M4 and x3850 X5 on which kernel would > get stuck in infinite loop creating duplicate sysfs files because, > for some reason, there are several duplicate boot entries in nvram > getting GetNextVariableName into a circle of iteration (with > period > 2). Also disable the workqueue, as efivar_update_sysfs_entries() uses GetNextVariableName() to figure out which variables have been created since the last iteration. That algorithm isn't going to work if GetNextVariableName() returns duplicates. Note that we don't disable EFI variable creation completely on the affected machines, it's just that any pstore dump-* files won't appear in sysfs until the next boot. Reported-by: Andre Heider Reported-by: Lingzhu Xiang Tested-by: Lingzhu Xiang Cc: Seiji Aguchi Cc: Signed-off-by: Matt Fleming [ Backported for 3.4-stable. Removed code related to pstore workqueue but pulled in helper function variable_is_present from a93bc0c; Moved the definition of __efivars to the top for being referenced in variable_is_present. ] Signed-off-by: Lingzhu Xiang Reviewed-by: CAI Qian Signed-off-by: Luis Henriques --- drivers/firmware/efivars.c | 66 +++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 63 insertions(+), 3 deletions(-) diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c index 9a1968e..2cbb675 100644 --- a/drivers/firmware/efivars.c +++ b/drivers/firmware/efivars.c @@ -122,6 +122,9 @@ struct efivar_attribute { ssize_t (*store)(struct efivar_entry *entry, const char *buf, size_t count); }; +static struct efivars __efivars; +static struct efivar_operations ops; + #define PSTORE_EFI_ATTRIBUTES \ (EFI_VARIABLE_NON_VOLATILE | \ EFI_VARIABLE_BOOTSERVICE_ACCESS | \ @@ -942,6 +945,28 @@ static ssize_t efivar_delete(struct file *filp, struct kobject *kobj, return count; } +static bool variable_is_present(efi_char16_t *variable_name, efi_guid_t *vendor) +{ + struct efivar_entry *entry, *n; + struct efivars *efivars = &__efivars; + unsigned long strsize1, strsize2; + bool found = false; + + strsize1 = utf16_strsize(variable_name, 1024); + list_for_each_entry_safe(entry, n, &efivars->list, list) { + strsize2 = utf16_strsize(entry->var.VariableName, 1024); + if (strsize1 == strsize2 && + !memcmp(variable_name, &(entry->var.VariableName), + strsize2) && + !efi_guidcmp(entry->var.VendorGuid, + *vendor)) { + found = true; + break; + } + } + return found; +} + /* * Returns the size of variable_name, in bytes, including the * terminating NULL character, or variable_name_size if no NULL @@ -1154,6 +1179,28 @@ void unregister_efivars(struct efivars *efivars) } EXPORT_SYMBOL_GPL(unregister_efivars); +/* + * Print a warning when duplicate EFI variables are encountered and + * disable the sysfs workqueue since the firmware is buggy. + */ +static void dup_variable_bug(efi_char16_t *s16, efi_guid_t *vendor_guid, + unsigned long len16) +{ + size_t i, len8 = len16 / sizeof(efi_char16_t); + char *s8; + + s8 = kzalloc(len8, GFP_KERNEL); + if (!s8) + return; + + for (i = 0; i < len8; i++) + s8[i] = s16[i]; + + printk(KERN_WARNING "efivars: duplicate variable: %s-%pUl\n", + s8, vendor_guid); + kfree(s8); +} + int register_efivars(struct efivars *efivars, const struct efivar_operations *ops, struct kobject *parent_kobj) @@ -1196,6 +1243,22 @@ int register_efivars(struct efivars *efivars, case EFI_SUCCESS: variable_name_size = var_name_strnsize(variable_name, variable_name_size); + + /* + * Some firmware implementations return the + * same variable name on multiple calls to + * get_next_variable(). Terminate the loop + * immediately as there is no guarantee that + * we'll ever see a different variable name, + * and may end up looping here forever. + */ + if (variable_is_present(variable_name, &vendor_guid)) { + dup_variable_bug(variable_name, &vendor_guid, + variable_name_size); + status = EFI_NOT_FOUND; + break; + } + efivar_create_sysfs_entry(efivars, variable_name_size, variable_name, @@ -1232,9 +1295,6 @@ out: } EXPORT_SYMBOL_GPL(register_efivars); -static struct efivars __efivars; -static struct efivar_operations ops; - /* * For now we register the efi subsystem with the firmware subsystem * and the vars subsystem with the efi subsystem. In the future, it