From 60e233a56609fd963c59e99bd75c663d63fa91b6 Mon Sep 17 00:00:00 2001 From: Bjørn Mork Date: Sun, 2 Sep 2012 15:41:34 +0200 Subject: kobject: fix oops with "input0: bad kobj_uevent_env content in show_uevent()" MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Cc: stable Signed-off-by: Greg Kroah-Hartman --- include/linux/kobject.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/kobject.h') diff --git a/include/linux/kobject.h b/include/linux/kobject.h index fc615a97e2d3..1e57449395b1 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) -- cgit v1.2.3-59-g8ed1b