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Date: Sun, 02 Sep 2012 15:41:34 +0200 From: Bjørn Mork <bjorn@...k.no> To: Fengguang Wu <fengguang.wu@...el.com> Cc: linux-input@...r.kernel.org, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, chunkeey@...glemail.com, linville@...driver.com, LKML <linux-kernel@...r.kernel.org> Subject: Re: input0: bad kobj_uevent_env content in show_uevent() Fengguang Wu <fengguang.wu@...el.com> 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: 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) Bjørn -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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