[PATCH 2/2] hfsplus: add a check for hfs_bnode_find

[PATCH 2/2] hfsplus: add a check for hfs_bnode_find

[Chuhong Yuan]

hfs_brec_update_parent misses a check for hfs_bnode_find and may miss
the failure.
Add a check for it like what is done in again.

Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
---
 fs/hfsplus/brec.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/hfsplus/brec.c b/fs/hfsplus/brec.c
index 1918544a7871..22bada8288c4 100644
--- a/fs/hfsplus/brec.c
+++ b/fs/hfsplus/brec.c
@@ -434,6 +434,8 @@ static int hfs_brec_update_parent(struct hfs_find_data *fd)
 			new_node->parent = tree->root;
 		}
 		fd->bnode = hfs_bnode_find(tree, new_node->parent);
+		if (IS_ERR(fd->bnode))
+			return PTR_ERR(fd->bnode);
 		/* create index key and entry */
 		hfs_bnode_read_key(new_node, fd->search_key, 14);
 		cnid = cpu_to_be32(new_node->this);
-- 
2.20.1

Re: [PATCH 2/2] hfsplus: add a check for hfs_bnode_find

[Ernesto A. Fernández]

Hi,

On Wed, Oct 16, 2019 at 08:06:20PM +0800, Chuhong Yuan wrote:
> hfs_brec_update_parent misses a check for hfs_bnode_find and may miss
> the failure.
> Add a check for it like what is done in again.
> 
> Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
> ---
>  fs/hfsplus/brec.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/fs/hfsplus/brec.c b/fs/hfsplus/brec.c
> index 1918544a7871..22bada8288c4 100644
> --- a/fs/hfsplus/brec.c
> +++ b/fs/hfsplus/brec.c
> @@ -434,6 +434,8 @@ static int hfs_brec_update_parent(struct hfs_find_data *fd)
>  			new_node->parent = tree->root;
>  		}
>  		fd->bnode = hfs_bnode_find(tree, new_node->parent);
> +		if (IS_ERR(fd->bnode))
> +			return PTR_ERR(fd->bnode);

You shouldn't just return here, you still hold a reference to new_node.
The call to hfs_bnode_find() after the again label seems to be making a
similar mistake.

I don't think either one can actually fail though, because the parent
nodes have all been read and hashed before, haven't they?

>  		/* create index key and entry */
>  		hfs_bnode_read_key(new_node, fd->search_key, 14);
>  		cnid = cpu_to_be32(new_node->this);
> -- 
> 2.20.1
> 

Re: [PATCH 2/2] hfsplus: add a check for hfs_bnode_find

[Chuhong Yuan]

On Thu, Oct 17, 2019 at 8:07 AM Ernesto A. Fernández
<ernesto.mnd.fernandez@gmail.com> wrote:
>
> Hi,
>
> On Wed, Oct 16, 2019 at 08:06:20PM +0800, Chuhong Yuan wrote:
> > hfs_brec_update_parent misses a check for hfs_bnode_find and may miss
> > the failure.
> > Add a check for it like what is done in again.
> >
> > Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
> > ---
> >  fs/hfsplus/brec.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/fs/hfsplus/brec.c b/fs/hfsplus/brec.c
> > index 1918544a7871..22bada8288c4 100644
> > --- a/fs/hfsplus/brec.c
> > +++ b/fs/hfsplus/brec.c
> > @@ -434,6 +434,8 @@ static int hfs_brec_update_parent(struct hfs_find_data *fd)
> >                       new_node->parent = tree->root;
> >               }
> >               fd->bnode = hfs_bnode_find(tree, new_node->parent);
> > +             if (IS_ERR(fd->bnode))
> > +                     return PTR_ERR(fd->bnode);
>
> You shouldn't just return here, you still hold a reference to new_node.
> The call to hfs_bnode_find() after the again label seems to be making a
> similar mistake.
>
> I don't think either one can actually fail though, because the parent
> nodes have all been read and hashed before, haven't they?
>

I find that after hfs_bnode_findhash in hfs_bnode_find, there is a test for
HFS_BNODE_ERROR and may return an error. I'm not sure whether it
can happen here.

> >               /* create index key and entry */
> >               hfs_bnode_read_key(new_node, fd->search_key, 14);
> >               cnid = cpu_to_be32(new_node->this);
> > --
> > 2.20.1
> >

Re: [PATCH 2/2] hfsplus: add a check for hfs_bnode_find

[Ernesto A. Fernández]

On Thu, Oct 17, 2019 at 09:30:20AM +0800, Chuhong Yuan wrote:
> On Thu, Oct 17, 2019 at 8:07 AM Ernesto A. Fernández
> <ernesto.mnd.fernandez@gmail.com> wrote:
> >
> > Hi,
> >
> > On Wed, Oct 16, 2019 at 08:06:20PM +0800, Chuhong Yuan wrote:
> > > hfs_brec_update_parent misses a check for hfs_bnode_find and may miss
> > > the failure.
> > > Add a check for it like what is done in again.
> > >
> > > Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
> > > ---
> > >  fs/hfsplus/brec.c | 2 ++
> > >  1 file changed, 2 insertions(+)
> > >
> > > diff --git a/fs/hfsplus/brec.c b/fs/hfsplus/brec.c
> > > index 1918544a7871..22bada8288c4 100644
> > > --- a/fs/hfsplus/brec.c
> > > +++ b/fs/hfsplus/brec.c
> > > @@ -434,6 +434,8 @@ static int hfs_brec_update_parent(struct hfs_find_data *fd)
> > >                       new_node->parent = tree->root;
> > >               }
> > >               fd->bnode = hfs_bnode_find(tree, new_node->parent);
> > > +             if (IS_ERR(fd->bnode))
> > > +                     return PTR_ERR(fd->bnode);
> >
> > You shouldn't just return here, you still hold a reference to new_node.
> > The call to hfs_bnode_find() after the again label seems to be making a
> > similar mistake.
> >
> > I don't think either one can actually fail though, because the parent
> > nodes have all been read and hashed before, haven't they?
> >
> 
> I find that after hfs_bnode_findhash in hfs_bnode_find, there is a test for
> HFS_BNODE_ERROR and may return an error. I'm not sure whether it
> can happen here.

That would require a race between hfs_bnode_find() and hfs_bnode_create(),
but the node has already been created.

> 
> > >               /* create index key and entry */
> > >               hfs_bnode_read_key(new_node, fd->search_key, 14);
> > >               cnid = cpu_to_be32(new_node->this);
> > > --
> > > 2.20.1
> > >

Re: [PATCH 2/2] hfsplus: add a check for hfs_bnode_find

[Viacheslav Dubeyko]

Sorry, I had some glitch during message sending. I am repeating the message sending.

> On Oct 17, 2019, at 11:52 PM, Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.com> wrote:
> 
> On Thu, Oct 17, 2019 at 09:30:20AM +0800, Chuhong Yuan wrote:
>> On Thu, Oct 17, 2019 at 8:07 AM Ernesto A. Fernández
>> <ernesto.mnd.fernandez@gmail.com> wrote:
>>> 
>>> Hi,
>>> 
>>> On Wed, Oct 16, 2019 at 08:06:20PM +0800, Chuhong Yuan wrote:
>>>> hfs_brec_update_parent misses a check for hfs_bnode_find and may miss
>>>> the failure.
>>>> Add a check for it like what is done in again.
>>>> 
>>>> Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
>>>> ---
>>>> fs/hfsplus/brec.c | 2 ++
>>>> 1 file changed, 2 insertions(+)
>>>> 
>>>> diff --git a/fs/hfsplus/brec.c b/fs/hfsplus/brec.c
>>>> index 1918544a7871..22bada8288c4 100644
>>>> --- a/fs/hfsplus/brec.c
>>>> +++ b/fs/hfsplus/brec.c
>>>> @@ -434,6 +434,8 @@ static int hfs_brec_update_parent(struct hfs_find_data *fd)
>>>>                      new_node->parent = tree->root;
>>>>              }
>>>>              fd->bnode = hfs_bnode_find(tree, new_node->parent);
>>>> +             if (IS_ERR(fd->bnode))
>>>> +                     return PTR_ERR(fd->bnode);
>>> 
>>> You shouldn't just return here, you still hold a reference to new_node.
>>> The call to hfs_bnode_find() after the again label seems to be making a
>>> similar mistake.
>>> 
>>> I don't think either one can actually fail though, because the parent
>>> nodes have all been read and hashed before, haven't they?
>>> 
>> 
>> I find that after hfs_bnode_findhash in hfs_bnode_find, there is a test for
>> HFS_BNODE_ERROR and may return an error. I'm not sure whether it
>> can happen here.
> 
> That would require a race between hfs_bnode_find() and hfs_bnode_create(),
> but the node has already been created.
> 

The whole function hfs_brec_update_parent() looks like the cycle. And there are several
places where PTR_ERR(node) is returned with error ([1] - [2]). So, it sounds that it needs
to follow this pattern or to rework these cases too. And, by the way, what if the node pointer
will be NULL?

Thanks,
Viacheslav Dubeyko.

[1] https://elixir.bootlin.com/linux/latest/source/fs/hfsplus/brec.c#L371
[2] https://elixir.bootlin.com/linux/latest/source/fs/hfsplus/brec.c#L402


>> 
>>>>              /* create index key and entry */
>>>>              hfs_bnode_read_key(new_node, fd->search_key, 14);
>>>>              cnid = cpu_to_be32(new_node->this);
>>>> --
>>>> 2.20.1