• Bjørn Mork's avatar
    kobject: fix oops with "input0: bad kobj_uevent_env content in show_uevent()" · 60e233a5
    Bjørn Mork authored
    Fengguang Wu <fengguang.wu@intel.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.
    
    [ 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: default avatarFengguang Wu <fengguang.wu@intel.com>
    Signed-off-by: Bjørn Mork's avatarBjørn Mork <bjorn@mork.no>
    Tested-by: default avatarFengguang Wu <fengguang.wu@intel.com>
    Cc: stable <stable@vger.kernel.org>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    60e233a5
kobject.h 7.06 KB