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[PATCH] ocfs2: update d_splice_alias() return code checking

Tetsuo Handa posted 1 patch 3 months, 2 weeks ago
There is a newer version of this series
fs/ocfs2/namei.c | 2 ++
1 file changed, 2 insertions(+)
[PATCH] ocfs2: update d_splice_alias() return code checking
Posted by Tetsuo Handa 3 months, 2 weeks ago 
When commit d3556babd7fa ("ocfs2: fix d_splice_alias() return code
checking") was merged into v3.18-rc3, d_splice_alias() was returning
one of a valid dentry, NULL or an ERR_PTR.

But when commit b5ae6b15bd73 ("merge d_materialise_unique() into
d_splice_alias()") was merged into v3.19-rc1, d_splice_alias() started
returning -ELOOP as one of ERR_PTR values.

As a result, when syzkaller mounts a crafted ocfs2 filesystem image that
hits d_splice_alias() == -ELOOP case from ocfs2_lookup(), ocfs2_lookup()
fails to handle -ELOOP case and generic_shutdown_super() hits "VFS: Busy
inodes after unmount" message.

Don't call ocfs2_dentry_attach_lock() nor ocfs2_dentry_attach_gen()
when d_splice_alias() returned -ELOOP.

Reported-by: syzbot <syzbot+1134d3a5b062e9665a7a@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=1134d3a5b062e9665a7a
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
---
This patch wants review from maintainers. I'm not familiar with this change.

 fs/ocfs2/namei.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/ocfs2/namei.c b/fs/ocfs2/namei.c
index 99278c8f0e24..4ccb39f43bc6 100644
--- a/fs/ocfs2/namei.c
+++ b/fs/ocfs2/namei.c
@@ -142,6 +142,8 @@ static struct dentry *ocfs2_lookup(struct inode *dir, struct dentry *dentry,
 
 bail_add:
 	ret = d_splice_alias(inode, dentry);
+	if (ret == ERR_PTR(-ELOOP))
+		goto bail_unlock;
 
 	if (inode) {
 		/*
-- 
2.49.0
Re: [PATCH] ocfs2: update d_splice_alias() return code checking
Posted by Al Viro 3 months, 2 weeks ago 
On Thu, Jun 26, 2025 at 11:14:59AM +0900, Tetsuo Handa wrote:

> But when commit b5ae6b15bd73 ("merge d_materialise_unique() into
> d_splice_alias()") was merged into v3.19-rc1, d_splice_alias() started
> returning -ELOOP as one of ERR_PTR values.
> 
> As a result, when syzkaller mounts a crafted ocfs2 filesystem image that
> hits d_splice_alias() == -ELOOP case from ocfs2_lookup(), ocfs2_lookup()
> fails to handle -ELOOP case and generic_shutdown_super() hits "VFS: Busy
> inodes after unmount" message.
> 
> Don't call ocfs2_dentry_attach_lock() nor ocfs2_dentry_attach_gen()
> when d_splice_alias() returned -ELOOP.
> 
> Reported-by: syzbot <syzbot+1134d3a5b062e9665a7a@syzkaller.appspotmail.com>
> Closes: https://syzkaller.appspot.com/bug?extid=1134d3a5b062e9665a7a
> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> ---
> This patch wants review from maintainers. I'm not familiar with this change.

Not the right fix.  If nothing else, -ELOOP is not the only possible value
there.

This
                status = ocfs2_dentry_attach_lock(dentry, inode,
                                                  OCFS2_I(dir)->ip_blkno);
                if (status) {
                        mlog_errno(status);
                        ret = ERR_PTR(status);
                        goto bail_unlock;
                }
looks like pretty obvious leak in its own right?  What's more, on IS_ERR(ret)
we should stop playing silly buggers and just return the damn error.

So basically
        ret = d_splice_alias(inode, dentry);
	if (IS_ERR(ret))
		goto bail_unlock;
	if (inode) {
		if (ret)
			dentry = ret;
                status = ocfs2_dentry_attach_lock(dentry, inode,
                                                  OCFS2_I(dir)->ip_blkno);
		if (unlikely(status)) {
			if (ret)
				dput(ret);
			ret = ERR_PTR(status);
		}
	} else {
                ocfs2_dentry_attach_gen(dentry);
	}
bail_unlock:
[PATCH v2] ocfs2: update d_splice_alias() return code checking
Posted by Tetsuo Handa 3 months, 1 week ago 
When commit d3556babd7fa ("ocfs2: fix d_splice_alias() return code
checking") was merged into v3.18-rc3, d_splice_alias() was returning
one of a valid dentry, NULL or an ERR_PTR.

When commit b5ae6b15bd73 ("merge d_materialise_unique() into
d_splice_alias()") was merged into v3.19-rc1, d_splice_alias() started
returning -ELOOP as one of ERR_PTR values.

Now, when syzkaller mounts a crafted ocfs2 filesystem image that hits
d_splice_alias() == -ELOOP case from ocfs2_lookup(), ocfs2_lookup() fails
to handle -ELOOP case and generic_shutdown_super() hits "VFS: Busy inodes
after unmount" message.

Instead of calling ocfs2_dentry_attach_lock() or ocfs2_dentry_attach_gen()
when d_splice_alias() returned an ERR_PTR value, change ocfs2_lookup() to
bail out immediately.

Also, ocfs2_lookup() needs to call dupt() when ocfs2_dentry_attach_lock()
returned an ERR_PTR value.

Reported-by: syzbot <syzbot+1134d3a5b062e9665a7a@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=1134d3a5b062e9665a7a
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
---
 fs/ocfs2/namei.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/fs/ocfs2/namei.c b/fs/ocfs2/namei.c
index 99278c8f0e24..f75fd19974bc 100644
--- a/fs/ocfs2/namei.c
+++ b/fs/ocfs2/namei.c
@@ -142,6 +142,8 @@ static struct dentry *ocfs2_lookup(struct inode *dir, struct dentry *dentry,
 
 bail_add:
 	ret = d_splice_alias(inode, dentry);
+	if (IS_ERR(ret))
+		goto bail_unlock;
 
 	if (inode) {
 		/*
@@ -154,13 +156,12 @@ static struct dentry *ocfs2_lookup(struct inode *dir, struct dentry *dentry,
 		 * NOTE: This dentry already has ->d_op set from
 		 * ocfs2_get_parent() and ocfs2_get_dentry()
 		 */
-		if (!IS_ERR_OR_NULL(ret))
-			dentry = ret;
-
-		status = ocfs2_dentry_attach_lock(dentry, inode,
+		status = ocfs2_dentry_attach_lock(ret ? ret : dentry, inode,
 						  OCFS2_I(dir)->ip_blkno);
 		if (status) {
 			mlog_errno(status);
+			if (ret)
+				dput(ret);
 			ret = ERR_PTR(status);
 			goto bail_unlock;
 		}
-- 
2.50.0
Re: [PATCH v2] ocfs2: update d_splice_alias() return code checking
Posted by Joseph Qi 3 months, 1 week ago 

On 2025/6/27 22:19, Tetsuo Handa wrote:
> When commit d3556babd7fa ("ocfs2: fix d_splice_alias() return code
> checking") was merged into v3.18-rc3, d_splice_alias() was returning
> one of a valid dentry, NULL or an ERR_PTR.
> 
> When commit b5ae6b15bd73 ("merge d_materialise_unique() into
> d_splice_alias()") was merged into v3.19-rc1, d_splice_alias() started
> returning -ELOOP as one of ERR_PTR values.
> 
> Now, when syzkaller mounts a crafted ocfs2 filesystem image that hits
> d_splice_alias() == -ELOOP case from ocfs2_lookup(), ocfs2_lookup() fails
> to handle -ELOOP case and generic_shutdown_super() hits "VFS: Busy inodes
> after unmount" message.
> 
> Instead of calling ocfs2_dentry_attach_lock() or ocfs2_dentry_attach_gen()
> when d_splice_alias() returned an ERR_PTR value, change ocfs2_lookup() to
> bail out immediately.
> 
> Also, ocfs2_lookup() needs to call dupt() when ocfs2_dentry_attach_lock()
> returned an ERR_PTR value.
> 
> Reported-by: syzbot <syzbot+1134d3a5b062e9665a7a@syzkaller.appspotmail.com>
> Closes: https://syzkaller.appspot.com/bug?extid=1134d3a5b062e9665a7a
> Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> ---
>  fs/ocfs2/namei.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/ocfs2/namei.c b/fs/ocfs2/namei.c
> index 99278c8f0e24..f75fd19974bc 100644
> --- a/fs/ocfs2/namei.c
> +++ b/fs/ocfs2/namei.c
> @@ -142,6 +142,8 @@ static struct dentry *ocfs2_lookup(struct inode *dir, struct dentry *dentry,
>  
>  bail_add:
>  	ret = d_splice_alias(inode, dentry);
> +	if (IS_ERR(ret))
> +		goto bail_unlock;
>  
>  	if (inode) {
>  		/*
> @@ -154,13 +156,12 @@ static struct dentry *ocfs2_lookup(struct inode *dir, struct dentry *dentry,
>  		 * NOTE: This dentry already has ->d_op set from
>  		 * ocfs2_get_parent() and ocfs2_get_dentry()
>  		 */
> -		if (!IS_ERR_OR_NULL(ret))
> -			dentry = ret;
> -

I'd like change this to:
if (ret)
	dentry = ret;

Instead of using "ret ? ret : dentry" below calling ocfs2_dentry_attach_lock().

> -		status = ocfs2_dentry_attach_lock(dentry, inode,
> +		status = ocfs2_dentry_attach_lock(ret ? ret : dentry, inode,
>  						  OCFS2_I(dir)->ip_blkno);
>  		if (status) {
>  			mlog_errno(status);
> +			if (ret)
> +				dput(ret);
>  			ret = ERR_PTR(status);
>  			goto bail_unlock;

The "goto" here can be eliminated since it has no real effect.

Thanks,
Joseph

>  		}
[PATCH v3] ocfs2: update d_splice_alias() return code checking
Posted by Tetsuo Handa 3 months, 1 week ago 
When commit d3556babd7fa ("ocfs2: fix d_splice_alias() return code
checking") was merged into v3.18-rc3, d_splice_alias() was returning
one of a valid dentry, NULL or an ERR_PTR.

When commit b5ae6b15bd73 ("merge d_materialise_unique() into
d_splice_alias()") was merged into v3.19-rc1, d_splice_alias() started
returning -ELOOP as one of ERR_PTR values.

Now, when syzkaller mounts a crafted ocfs2 filesystem image that hits
d_splice_alias() == -ELOOP case from ocfs2_lookup(), ocfs2_lookup() fails
to handle -ELOOP case and generic_shutdown_super() hits "VFS: Busy inodes
after unmount" message.

Instead of calling ocfs2_dentry_attach_lock() or ocfs2_dentry_attach_gen()
when d_splice_alias() returned an ERR_PTR value, change ocfs2_lookup() to
bail out immediately.

Also, ocfs2_lookup() needs to call dupt() when ocfs2_dentry_attach_lock()
returned an ERR_PTR value.

Reported-by: syzbot <syzbot+1134d3a5b062e9665a7a@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=1134d3a5b062e9665a7a
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
---
 fs/ocfs2/namei.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/ocfs2/namei.c b/fs/ocfs2/namei.c
index 99278c8f0e24..721580dfce3a 100644
--- a/fs/ocfs2/namei.c
+++ b/fs/ocfs2/namei.c
@@ -142,6 +142,8 @@ static struct dentry *ocfs2_lookup(struct inode *dir, struct dentry *dentry,
 
 bail_add:
 	ret = d_splice_alias(inode, dentry);
+	if (IS_ERR(ret))
+		goto bail_unlock;
 
 	if (inode) {
 		/*
@@ -154,15 +156,16 @@ static struct dentry *ocfs2_lookup(struct inode *dir, struct dentry *dentry,
 		 * NOTE: This dentry already has ->d_op set from
 		 * ocfs2_get_parent() and ocfs2_get_dentry()
 		 */
-		if (!IS_ERR_OR_NULL(ret))
+		if (ret)
 			dentry = ret;
 
 		status = ocfs2_dentry_attach_lock(dentry, inode,
 						  OCFS2_I(dir)->ip_blkno);
 		if (status) {
 			mlog_errno(status);
+			if (ret)
+				dput(ret);
 			ret = ERR_PTR(status);
-			goto bail_unlock;
 		}
 	} else
 		ocfs2_dentry_attach_gen(dentry);
-- 
2.47.1
Re: [PATCH v3] ocfs2: update d_splice_alias() return code checking
Posted by Joseph Qi 3 months, 1 week ago 

On 2025/6/30 18:21, Tetsuo Handa wrote:
> When commit d3556babd7fa ("ocfs2: fix d_splice_alias() return code
> checking") was merged into v3.18-rc3, d_splice_alias() was returning
> one of a valid dentry, NULL or an ERR_PTR.
> 
> When commit b5ae6b15bd73 ("merge d_materialise_unique() into
> d_splice_alias()") was merged into v3.19-rc1, d_splice_alias() started
> returning -ELOOP as one of ERR_PTR values.
> 
> Now, when syzkaller mounts a crafted ocfs2 filesystem image that hits
> d_splice_alias() == -ELOOP case from ocfs2_lookup(), ocfs2_lookup() fails
> to handle -ELOOP case and generic_shutdown_super() hits "VFS: Busy inodes
> after unmount" message.
> 
> Instead of calling ocfs2_dentry_attach_lock() or ocfs2_dentry_attach_gen()
> when d_splice_alias() returned an ERR_PTR value, change ocfs2_lookup() to
> bail out immediately.
> 
> Also, ocfs2_lookup() needs to call dupt() when ocfs2_dentry_attach_lock()
> returned an ERR_PTR value.
> 
> Reported-by: syzbot <syzbot+1134d3a5b062e9665a7a@syzkaller.appspotmail.com>
> Closes: https://syzkaller.appspot.com/bug?extid=1134d3a5b062e9665a7a
> Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

Looks fine to me.
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>

> ---
>  fs/ocfs2/namei.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ocfs2/namei.c b/fs/ocfs2/namei.c
> index 99278c8f0e24..721580dfce3a 100644
> --- a/fs/ocfs2/namei.c
> +++ b/fs/ocfs2/namei.c
> @@ -142,6 +142,8 @@ static struct dentry *ocfs2_lookup(struct inode *dir, struct dentry *dentry,
>  
>  bail_add:
>  	ret = d_splice_alias(inode, dentry);
> +	if (IS_ERR(ret))
> +		goto bail_unlock;
>  
>  	if (inode) {
>  		/*
> @@ -154,15 +156,16 @@ static struct dentry *ocfs2_lookup(struct inode *dir, struct dentry *dentry,
>  		 * NOTE: This dentry already has ->d_op set from
>  		 * ocfs2_get_parent() and ocfs2_get_dentry()
>  		 */
> -		if (!IS_ERR_OR_NULL(ret))
> +		if (ret)
>  			dentry = ret;
>  
>  		status = ocfs2_dentry_attach_lock(dentry, inode,
>  						  OCFS2_I(dir)->ip_blkno);
>  		if (status) {
>  			mlog_errno(status);
> +			if (ret)
> +				dput(ret);
>  			ret = ERR_PTR(status);
> -			goto bail_unlock;
>  		}
>  	} else
>  		ocfs2_dentry_attach_gen(dentry);

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