Messages in this thread | | | Date | Thu, 23 Sep 2010 16:19:19 -0400 | From | Valerie Aurora <> | Subject | Re: [PATCH 5/7 v3] vfs: fix possible use after free in finish_open() |
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On Mon, Sep 20, 2010 at 08:04:09PM +0200, Miklos Szeredi wrote: > From: Miklos Szeredi <mszeredi@suse.cz> > > If open(O_TRUNC) is called and the actual open fails, then nd->path > will be released by nameidata_to_filp(). If this races with an > unmount then mnt_drop_write() can Oops. > > Fix by acquiring a ref to nd->path and releasing after > mnt_drop_write(). > > Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> > CC: stable@kernel.org > --- > fs/namei.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > Index: linux-2.6/fs/namei.c > =================================================================== > --- linux-2.6.orig/fs/namei.c 2010-09-20 13:32:35.000000000 +0200 > +++ linux-2.6/fs/namei.c 2010-09-20 13:33:14.000000000 +0200 > @@ -1559,6 +1559,11 @@ static struct file *finish_open(struct n > mnt_drop_write(nd->path.mnt); > goto exit; > } > + if (will_truncate) { > + /* nameidata_to_filp() puts nd->path! */ > + path_get(&nd->path); > + } > + > filp = nameidata_to_filp(nd); > if (!IS_ERR(filp)) { > error = ima_file_check(filp, acc_mode); > @@ -1581,8 +1586,10 @@ static struct file *finish_open(struct n > * because the filp has had a write taken > * on its behalf. > */ > - if (will_truncate) > + if (will_truncate) { > mnt_drop_write(nd->path.mnt); > + path_put(&nd->path); > + } > return filp; > > exit: >
Nice catch!
Reviewed-by: Valerie Aurora <vaurora@redhat.com>
-VAL
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