From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753884Ab2IQBUL (ORCPT ); Sun, 16 Sep 2012 21:20:11 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:33599 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753356Ab2IQAuJ (ORCPT ); Sun, 16 Sep 2012 20:50:09 -0400 Message-Id: <20120917003642.279358860@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Mon, 17 Sep 2012 01:38:21 +0100 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, =?UTF-8?q?Bj=C3=B8rn=20Mork?= , Fengguang Wu , Greg Kroah-Hartman Subject: [ 116/135] kobject: fix oops with "input0: bad kobj_uevent_env content in show_uevent()" In-Reply-To: <20120917003625.784119135@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:21c:bfff:fe03:f805 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Bjørn Mork commit 60e233a56609fd963c59e99bd75c663d63fa91b6 upstream. Fengguang Wu writes: > After the __devinit* removal series, I can still get kernel panic in > show_uevent(). So there are more sources of bug.. > > Debug patch: > > @@ -343,8 +343,11 @@ static ssize_t show_uevent(struct device > goto out; > > /* copy keys to file */ > - for (i = 0; i < env->envp_idx; i++) > + dev_err(dev, "uevent %d env[%d]: %s/.../%s\n", env->buflen, env->envp_idx, top_kobj->name, dev->kobj.name); > + for (i = 0; i < env->envp_idx; i++) { > + printk(KERN_ERR "uevent %d env[%d]: %s\n", (int)count, i, env->envp[i]); > count += sprintf(&buf[count], "%s\n", env->envp[i]); > + } > > Oops message, the env[] is again not properly initilized: > > [ 44.068623] input input0: uevent 61 env[805306368]: input0/.../input0 > [ 44.069552] uevent 0 env[0]: (null) This is a completely different CONFIG_HOTPLUG problem, only demonstrating another reason why CONFIG_HOTPLUG should go away. I had a hard time trying to disable it anyway ;-) The problem this time is lots of code assuming that a call to add_uevent_var() will guarantee that env->buflen > 0. This is not true if CONFIG_HOTPLUG is unset. So things like this end up overwriting env->envp_idx because the array index is -1: if (add_uevent_var(env, "MODALIAS=")) return -ENOMEM; len = input_print_modalias(&env->buf[env->buflen - 1], sizeof(env->buf) - env->buflen, dev, 0); Don't know what the best action is, given that there seem to be a *lot* of this around the kernel. This patch "fixes" the problem for me, but I don't know if it can be considered an appropriate fix. [ It is the correct fix for now, for 3.7 forcing CONFIG_HOTPLUG to always be on is the longterm fix, but it's too late for 3.6 and older kernels to resolve this that way - gregkh ] Reported-by: Fengguang Wu Signed-off-by: Bjørn Mork Tested-by: Fengguang Wu Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- include/linux/kobject.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/kobject.h b/include/linux/kobject.h index fc615a9..1e57449 100644 --- a/include/linux/kobject.h +++ b/include/linux/kobject.h @@ -224,7 +224,7 @@ static inline int kobject_uevent_env(struct kobject *kobj, static inline __printf(2, 3) int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...) -{ return 0; } +{ return -ENOMEM; } static inline int kobject_action_type(const char *buf, size_t count, enum kobject_action *type)