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| author | Bjørn Mork <bjorn@mork.no> | 2012-09-02 15:41:34 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-10-02 10:29:55 -0700 |
| commit | cf499a04f9b5c8d2218257046b66b3062401673a (patch) | |
| tree | 9c9930f689aa9df537462aed2e08e423dd181a3a | |
| parent | f0868b703758f19c2ced945c2c3fce1c151ab369 (diff) | |
| download | lwn-cf499a04f9b5c8d2218257046b66b3062401673a.tar.gz lwn-cf499a04f9b5c8d2218257046b66b3062401673a.zip | |
kobject: fix oops with "input0: bad kobj_uevent_env content in show_uevent()"
commit 60e233a56609fd963c59e99bd75c663d63fa91b6 upstream.
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: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Tested-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | include/linux/kobject.h | 2 |
1 files changed, 1 insertions, 1 deletions
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) |