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authorBjørn Mork <bjorn@mork.no>2012-09-02 15:41:34 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-10-02 09:47:25 -0700
commitf8ec0c2008088108f6d4919ed2013bbca1651d13 (patch)
treea527bfaa2511a687049929daa4c17a3579b1e686 /include/linux/kobject.h
parentad0b57d5fc1e7ce32e8d693ae0b8ea6df3eb63b3 (diff)
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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>
Diffstat (limited to 'include/linux/kobject.h')
-rw-r--r--include/linux/kobject.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/kobject.h b/include/linux/kobject.h
index 9229b64..b557c78 100644
--- a/include/linux/kobject.h
+++ b/include/linux/kobject.h
@@ -228,7 +228,7 @@ static inline int kobject_uevent_env(struct kobject *kobj,
static inline __attribute__((format(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)