2010-06-21 09:51:01

by Davidlohr Bueso

Subject: [PATCH fs/ramfs] inode.c: Fix incorrect variable freeing.

Hi,

In ramfs_fill_super(), if fsi's memory allocation fails, it will go to 'fail',
which immediately tries to free the variable, potentially producing an Oops.
This patch addresses this issue.

Thanks.

Signed-off-by: Davidlohr Bueso <[email protected]>
---
fs/ramfs/inode.c | 8 +++++---
1 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/fs/ramfs/inode.c b/fs/ramfs/inode.c
index a5ebae7..40af7a2 100644
--- a/fs/ramfs/inode.c
+++ b/fs/ramfs/inode.c
@@ -219,7 +219,7 @@ int ramfs_fill_super(struct super_block *sb, void *data, int silent)
sb->s_fs_info = fsi;
if (!fsi) {
err = -ENOMEM;
- goto fail;
+ goto fail2;
}

err = ramfs_parse_options(data, &fsi->mount_opts);
@@ -247,11 +247,13 @@ int ramfs_fill_super(struct super_block *sb, void *data, int silent)
}

return 0;
-fail:
- kfree(fsi);
+fail2:
sb->s_fs_info = NULL;
iput(inode);
return err;
+fail:
+ kfree(fsi);
+ goto fail2;
}

int ramfs_get_sb(struct file_system_type *fs_type,
--
1.7.0.4

2010-06-22 19:41:32

by Andrew Morton

Subject: Re: [PATCH fs/ramfs] inode.c: Fix incorrect variable freeing.

On Sun, 20 Jun 2010 15:27:37 -0400
Davidlohr Bueso <[email protected]> wrote:

> Hi,
>
> In ramfs_fill_super(), if fsi's memory allocation fails, it will go to 'fail',
> which immediately tries to free the variable, potentially producing an Oops.
> This patch addresses this issue.
>
> Thanks.
>
> Signed-off-by: Davidlohr Bueso <[email protected]>
> ---
> fs/ramfs/inode.c | 8 +++++---
> 1 files changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/fs/ramfs/inode.c b/fs/ramfs/inode.c
> index a5ebae7..40af7a2 100644
> --- a/fs/ramfs/inode.c
> +++ b/fs/ramfs/inode.c
> @@ -219,7 +219,7 @@ int ramfs_fill_super(struct super_block *sb, void *data, int silent)
> sb->s_fs_info = fsi;
> if (!fsi) {
> err = -ENOMEM;
> - goto fail;
> + goto fail2;
> }
>
> err = ramfs_parse_options(data, &fsi->mount_opts);
> @@ -247,11 +247,13 @@ int ramfs_fill_super(struct super_block *sb, void *data, int silent)
> }
>
> return 0;
> -fail:
> - kfree(fsi);
> +fail2:
> sb->s_fs_info = NULL;
> iput(inode);
> return err;
> +fail:
> + kfree(fsi);
> + goto fail2;
> }
>
> int ramfs_get_sb(struct file_system_type *fs_type,

notabug. kfree(NULL) is an OK thing to do. The kernel does this
pretty regularly in recovery paths - it usually results in slightly
simpler and slightly smaller code.

2010-06-23 13:21:36

by Davidlohr Bueso

Subject: Re: [PATCH fs/ramfs] inode.c: Fix incorrect variable freeing.

On Tue, 2010-06-22 at 12:41 -0700, Andrew Morton wrote:
> On Sun, 20 Jun 2010 15:27:37 -0400
> Davidlohr Bueso <[email protected]> wrote:
>
> > Hi,
> >
> > In ramfs_fill_super(), if fsi's memory allocation fails, it will go to 'fail',
> > which immediately tries to free the variable, potentially producing an Oops.
> > This patch addresses this issue.
> >
> > Thanks.
> >
> > Signed-off-by: Davidlohr Bueso <[email protected]>
> > ---
> > fs/ramfs/inode.c | 8 +++++---
> > 1 files changed, 5 insertions(+), 3 deletions(-)
> >
> > diff --git a/fs/ramfs/inode.c b/fs/ramfs/inode.c
> > index a5ebae7..40af7a2 100644
> > --- a/fs/ramfs/inode.c
> > +++ b/fs/ramfs/inode.c
> > @@ -219,7 +219,7 @@ int ramfs_fill_super(struct super_block *sb, void *data, int silent)
> > sb->s_fs_info = fsi;
> > if (!fsi) {
> > err = -ENOMEM;
> > - goto fail;
> > + goto fail2;
> > }
> >
> > err = ramfs_parse_options(data, &fsi->mount_opts);
> > @@ -247,11 +247,13 @@ int ramfs_fill_super(struct super_block *sb, void *data, int silent)
> > }
> >
> > return 0;
> > -fail:
> > - kfree(fsi);
> > +fail2:
> > sb->s_fs_info = NULL;
> > iput(inode);
> > return err;
> > +fail:
> > + kfree(fsi);
> > + goto fail2;
> > }
> >
> > int ramfs_get_sb(struct file_system_type *fs_type,
>
> notabug. kfree(NULL) is an OK thing to do. The kernel does this
> pretty regularly in recovery paths - it usually results in slightly
> simpler and slightly smaller code.

Yeah I kind of knew that but slipped my mind. Sorry for the noise.