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[PATCH] fs: erofs: remember if kobject_init_and_add was done

Dongliang Mu posted 1 patch 4 years, 3 months ago 
fs/erofs/internal.h | 1 +
fs/erofs/sysfs.c    | 9 ++++++---
2 files changed, 7 insertions(+), 3 deletions(-)
[PATCH] fs: erofs: remember if kobject_init_and_add was done
Posted by Dongliang Mu 4 years, 3 months ago 
From: Dongliang Mu <mudongliangabcd@gmail.com>

Syzkaller hit 'WARNING: kobject bug in erofs_unregister_sysfs'. This bug
is triggered by injecting fault in kobject_init_and_add of
erofs_unregister_sysfs.

Fix this by remembering if kobject_init_and_add is successful.

Note that I've tested the patch and the crash does not occur any more.

Reported-by: syzkaller <syzkaller@googlegroups.com>
Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
---
 fs/erofs/internal.h | 1 +
 fs/erofs/sysfs.c    | 9 ++++++---
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 5aa2cf2c2f80..9e20665e3f68 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -144,6 +144,7 @@ struct erofs_sb_info {
 	u32 feature_incompat;
 
 	/* sysfs support */
+	bool s_sysfs_inited;
 	struct kobject s_kobj;		/* /sys/fs/erofs/<devname> */
 	struct completion s_kobj_unregister;
 };
diff --git a/fs/erofs/sysfs.c b/fs/erofs/sysfs.c
index dac252bc9228..2b48a4df19b4 100644
--- a/fs/erofs/sysfs.c
+++ b/fs/erofs/sysfs.c
@@ -209,6 +209,7 @@ int erofs_register_sysfs(struct super_block *sb)
 				   "%s", sb->s_id);
 	if (err)
 		goto put_sb_kobj;
+	sbi->s_sysfs_inited = true;
 	return 0;
 
 put_sb_kobj:
@@ -221,9 +222,11 @@ void erofs_unregister_sysfs(struct super_block *sb)
 {
 	struct erofs_sb_info *sbi = EROFS_SB(sb);
 
-	kobject_del(&sbi->s_kobj);
-	kobject_put(&sbi->s_kobj);
-	wait_for_completion(&sbi->s_kobj_unregister);
+	if (sbi->s_sysfs_inited) {
+		kobject_del(&sbi->s_kobj);
+		kobject_put(&sbi->s_kobj);
+		wait_for_completion(&sbi->s_kobj_unregister);
+	}
 }
 
 int __init erofs_init_sysfs(void)
-- 
2.25.1
Re: [PATCH] fs: erofs: remember if kobject_init_and_add was done
Posted by Huang Jianan 4 years, 3 months ago 
在 2022/3/15 15:51, Dongliang Mu 写道:
> From: Dongliang Mu <mudongliangabcd@gmail.com>
>
> Syzkaller hit 'WARNING: kobject bug in erofs_unregister_sysfs'. This bug
> is triggered by injecting fault in kobject_init_and_add of
> erofs_unregister_sysfs.
>
> Fix this by remembering if kobject_init_and_add is successful.
>
> Note that I've tested the patch and the crash does not occur any more.
>
> Reported-by: syzkaller <syzkaller@googlegroups.com>
> Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
> ---
>   fs/erofs/internal.h | 1 +
>   fs/erofs/sysfs.c    | 9 ++++++---
>   2 files changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
> index 5aa2cf2c2f80..9e20665e3f68 100644
> --- a/fs/erofs/internal.h
> +++ b/fs/erofs/internal.h
> @@ -144,6 +144,7 @@ struct erofs_sb_info {
>   	u32 feature_incompat;
>   
>   	/* sysfs support */
> +	bool s_sysfs_inited;

Hi Dongliang,

How about using sbi->s_kobj.state_in_sysfs to avoid adding a extra 
member in sbi ?

Thanks,
Jianan

>   	struct kobject s_kobj;		/* /sys/fs/erofs/<devname> */
>   	struct completion s_kobj_unregister;
>   };
> diff --git a/fs/erofs/sysfs.c b/fs/erofs/sysfs.c
> index dac252bc9228..2b48a4df19b4 100644
> --- a/fs/erofs/sysfs.c
> +++ b/fs/erofs/sysfs.c
> @@ -209,6 +209,7 @@ int erofs_register_sysfs(struct super_block *sb)
>   				   "%s", sb->s_id);
>   	if (err)
>   		goto put_sb_kobj;
> +	sbi->s_sysfs_inited = true;
>   	return 0;
>   
>   put_sb_kobj:
> @@ -221,9 +222,11 @@ void erofs_unregister_sysfs(struct super_block *sb)
>   {
>   	struct erofs_sb_info *sbi = EROFS_SB(sb);
>   
> -	kobject_del(&sbi->s_kobj);
> -	kobject_put(&sbi->s_kobj);
> -	wait_for_completion(&sbi->s_kobj_unregister);
> +	if (sbi->s_sysfs_inited) {
> +		kobject_del(&sbi->s_kobj);
> +		kobject_put(&sbi->s_kobj);
> +		wait_for_completion(&sbi->s_kobj_unregister);
> +	}
>   }
>   
>   int __init erofs_init_sysfs(void)
Re: [PATCH] fs: erofs: remember if kobject_init_and_add was done
Posted by Gao Xiang 4 years, 3 months ago 
On Tue, Mar 15, 2022 at 06:43:01PM +0800, Huang Jianan wrote:
> 在 2022/3/15 15:51, Dongliang Mu 写道:
> > From: Dongliang Mu <mudongliangabcd@gmail.com>
> > 
> > Syzkaller hit 'WARNING: kobject bug in erofs_unregister_sysfs'. This bug
> > is triggered by injecting fault in kobject_init_and_add of
> > erofs_unregister_sysfs.
> > 
> > Fix this by remembering if kobject_init_and_add is successful.
> > 
> > Note that I've tested the patch and the crash does not occur any more.
> > 
> > Reported-by: syzkaller <syzkaller@googlegroups.com>
> > Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
> > ---
> >   fs/erofs/internal.h | 1 +
> >   fs/erofs/sysfs.c    | 9 ++++++---
> >   2 files changed, 7 insertions(+), 3 deletions(-)
> > 
> > diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
> > index 5aa2cf2c2f80..9e20665e3f68 100644
> > --- a/fs/erofs/internal.h
> > +++ b/fs/erofs/internal.h
> > @@ -144,6 +144,7 @@ struct erofs_sb_info {
> >   	u32 feature_incompat;
> >   	/* sysfs support */
> > +	bool s_sysfs_inited;
> 
> Hi Dongliang,
> 
> How about using sbi->s_kobj.state_in_sysfs to avoid adding a extra member in
> sbi ?

Ok, I have no tendency of these (I'm fine with either ways).
I've seen some usage like:

static inline int device_is_registered(struct device *dev)
{
        return dev->kobj.state_in_sysfs;
}

But I'm still not sure if we need to rely on such internal
interface.. More thoughts?

Thanks,
Gao Xiang

> 
> Thanks,
> Jianan
> 
> >   	struct kobject s_kobj;		/* /sys/fs/erofs/<devname> */
> >   	struct completion s_kobj_unregister;
> >   };
> > diff --git a/fs/erofs/sysfs.c b/fs/erofs/sysfs.c
> > index dac252bc9228..2b48a4df19b4 100644
> > --- a/fs/erofs/sysfs.c
> > +++ b/fs/erofs/sysfs.c
> > @@ -209,6 +209,7 @@ int erofs_register_sysfs(struct super_block *sb)
> >   				   "%s", sb->s_id);
> >   	if (err)
> >   		goto put_sb_kobj;
> > +	sbi->s_sysfs_inited = true;
> >   	return 0;
> >   put_sb_kobj:
> > @@ -221,9 +222,11 @@ void erofs_unregister_sysfs(struct super_block *sb)
> >   {
> >   	struct erofs_sb_info *sbi = EROFS_SB(sb);
> > -	kobject_del(&sbi->s_kobj);
> > -	kobject_put(&sbi->s_kobj);
> > -	wait_for_completion(&sbi->s_kobj_unregister);
> > +	if (sbi->s_sysfs_inited) {
> > +		kobject_del(&sbi->s_kobj);
> > +		kobject_put(&sbi->s_kobj);
> > +		wait_for_completion(&sbi->s_kobj_unregister);
> > +	}
> >   }
> >   int __init erofs_init_sysfs(void)
Re: [PATCH] fs: erofs: remember if kobject_init_and_add was done
Posted by Huang Jianan 4 years, 3 months ago 
在 2022/3/15 18:55, Gao Xiang 写道:
> On Tue, Mar 15, 2022 at 06:43:01PM +0800, Huang Jianan wrote:
>> 在 2022/3/15 15:51, Dongliang Mu 写道:
>>> From: Dongliang Mu <mudongliangabcd@gmail.com>
>>>
>>> Syzkaller hit 'WARNING: kobject bug in erofs_unregister_sysfs'. This bug
>>> is triggered by injecting fault in kobject_init_and_add of
>>> erofs_unregister_sysfs.
>>>
>>> Fix this by remembering if kobject_init_and_add is successful.
>>>
>>> Note that I've tested the patch and the crash does not occur any more.
>>>
>>> Reported-by: syzkaller <syzkaller@googlegroups.com>
>>> Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
>>> ---
>>>    fs/erofs/internal.h | 1 +
>>>    fs/erofs/sysfs.c    | 9 ++++++---
>>>    2 files changed, 7 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
>>> index 5aa2cf2c2f80..9e20665e3f68 100644
>>> --- a/fs/erofs/internal.h
>>> +++ b/fs/erofs/internal.h
>>> @@ -144,6 +144,7 @@ struct erofs_sb_info {
>>>    	u32 feature_incompat;
>>>    	/* sysfs support */
>>> +	bool s_sysfs_inited;
>> Hi Dongliang,
>>
>> How about using sbi->s_kobj.state_in_sysfs to avoid adding a extra member in
>> sbi ?
> Ok, I have no tendency of these (I'm fine with either ways).
> I've seen some usage like:
>
> static inline int device_is_registered(struct device *dev)
> {
>          return dev->kobj.state_in_sysfs;
> }
>
> But I'm still not sure if we need to rely on such internal
> interface.. More thoughts?

Yeah... It seems that it is better to use some of the interfaces 
provided by kobject,
otherwise we should still maintain this state in sbi.

Thanks,
Jianan

> Thanks,
> Gao Xiang
>> Thanks,
>> Jianan
>>
>>>    	struct kobject s_kobj;		/* /sys/fs/erofs/<devname> */
>>>    	struct completion s_kobj_unregister;
>>>    };
>>> diff --git a/fs/erofs/sysfs.c b/fs/erofs/sysfs.c
>>> index dac252bc9228..2b48a4df19b4 100644
>>> --- a/fs/erofs/sysfs.c
>>> +++ b/fs/erofs/sysfs.c
>>> @@ -209,6 +209,7 @@ int erofs_register_sysfs(struct super_block *sb)
>>>    				   "%s", sb->s_id);
>>>    	if (err)
>>>    		goto put_sb_kobj;
>>> +	sbi->s_sysfs_inited = true;
>>>    	return 0;
>>>    put_sb_kobj:
>>> @@ -221,9 +222,11 @@ void erofs_unregister_sysfs(struct super_block *sb)
>>>    {
>>>    	struct erofs_sb_info *sbi = EROFS_SB(sb);
>>> -	kobject_del(&sbi->s_kobj);
>>> -	kobject_put(&sbi->s_kobj);
>>> -	wait_for_completion(&sbi->s_kobj_unregister);
>>> +	if (sbi->s_sysfs_inited) {
>>> +		kobject_del(&sbi->s_kobj);
>>> +		kobject_put(&sbi->s_kobj);
>>> +		wait_for_completion(&sbi->s_kobj_unregister);
>>> +	}
>>>    }
>>>    int __init erofs_init_sysfs(void)
Re: [PATCH] fs: erofs: remember if kobject_init_and_add was done
Posted by Dongliang Mu 4 years, 3 months ago 
On Tue, Mar 15, 2022 at 7:05 PM Huang Jianan <jnhuang95@gmail.com> wrote:
>
> 在 2022/3/15 18:55, Gao Xiang 写道:
> > On Tue, Mar 15, 2022 at 06:43:01PM +0800, Huang Jianan wrote:
> >> 在 2022/3/15 15:51, Dongliang Mu 写道:
> >>> From: Dongliang Mu <mudongliangabcd@gmail.com>
> >>>
> >>> Syzkaller hit 'WARNING: kobject bug in erofs_unregister_sysfs'. This bug
> >>> is triggered by injecting fault in kobject_init_and_add of
> >>> erofs_unregister_sysfs.
> >>>
> >>> Fix this by remembering if kobject_init_and_add is successful.
> >>>
> >>> Note that I've tested the patch and the crash does not occur any more.
> >>>
> >>> Reported-by: syzkaller <syzkaller@googlegroups.com>
> >>> Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
> >>> ---
> >>>    fs/erofs/internal.h | 1 +
> >>>    fs/erofs/sysfs.c    | 9 ++++++---
> >>>    2 files changed, 7 insertions(+), 3 deletions(-)
> >>>
> >>> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
> >>> index 5aa2cf2c2f80..9e20665e3f68 100644
> >>> --- a/fs/erofs/internal.h
> >>> +++ b/fs/erofs/internal.h
> >>> @@ -144,6 +144,7 @@ struct erofs_sb_info {
> >>>     u32 feature_incompat;
> >>>     /* sysfs support */
> >>> +   bool s_sysfs_inited;
> >> Hi Dongliang,
> >>
> >> How about using sbi->s_kobj.state_in_sysfs to avoid adding a extra member in
> >> sbi ?
> > Ok, I have no tendency of these (I'm fine with either ways).
> > I've seen some usage like:
> >
> > static inline int device_is_registered(struct device *dev)
> > {
> >          return dev->kobj.state_in_sysfs;
> > }
> >
> > But I'm still not sure if we need to rely on such internal
> > interface.. More thoughts?
>
> Yeah... It seems that it is better to use some of the interfaces
> provided by kobject,
> otherwise we should still maintain this state in sbi.
>

I am fine with either way. Let me know if you reach to an agreement.

> Thanks,
> Jianan
>
> > Thanks,
> > Gao Xiang
> >> Thanks,
> >> Jianan
> >>
> >>>     struct kobject s_kobj;          /* /sys/fs/erofs/<devname> */
> >>>     struct completion s_kobj_unregister;
> >>>    };
> >>> diff --git a/fs/erofs/sysfs.c b/fs/erofs/sysfs.c
> >>> index dac252bc9228..2b48a4df19b4 100644
> >>> --- a/fs/erofs/sysfs.c
> >>> +++ b/fs/erofs/sysfs.c
> >>> @@ -209,6 +209,7 @@ int erofs_register_sysfs(struct super_block *sb)
> >>>                                "%s", sb->s_id);
> >>>     if (err)
> >>>             goto put_sb_kobj;
> >>> +   sbi->s_sysfs_inited = true;
> >>>     return 0;
> >>>    put_sb_kobj:
> >>> @@ -221,9 +222,11 @@ void erofs_unregister_sysfs(struct super_block *sb)
> >>>    {
> >>>     struct erofs_sb_info *sbi = EROFS_SB(sb);
> >>> -   kobject_del(&sbi->s_kobj);
> >>> -   kobject_put(&sbi->s_kobj);
> >>> -   wait_for_completion(&sbi->s_kobj_unregister);
> >>> +   if (sbi->s_sysfs_inited) {
> >>> +           kobject_del(&sbi->s_kobj);
> >>> +           kobject_put(&sbi->s_kobj);
> >>> +           wait_for_completion(&sbi->s_kobj_unregister);
> >>> +   }
> >>>    }
> >>>    int __init erofs_init_sysfs(void)
>

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