On Tue, Oct 18, 2016 at 6:23 PM, Namhyung Kim wrote:
> When update_ms is set, pstore_get_records() will be called when there's
> a new entry. But unlink can be called at the same time and might
> contend with the open-read-close loop. Depending on the implementation
> of platform driver, it may be safe or not. But I think it'd be better
> to protect those race in the first place.
>
> Cc: Stefan Hajnoczi
> Signed-off-by: Namhyung Kim
This looks correct to me, thanks! It should appear in -next shortly...
-Kees
> ---
> fs/pstore/inode.c | 7 +--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
> index 1781dc50762e..75728dfae0a6 100644
> --- a/fs/pstore/inode.c
> +++ b/fs/pstore/inode.c
> @@ -197,11 +197,14 @@ static int pstore_unlink(struct inode *dir, struct
> dentry *dentry)
> if (err)
> return err;
>
> - if (p->psi->erase)
> + if (p->psi->erase) {
> + mutex_lock(&p->psi->read_mutex);
> p->psi->erase(p->type, p->id, p->count,
> d_inode(dentry)->i_ctime, p->psi);
> - else
> + mutex_unlock(&p->psi->read_mutex);
> + } else {
> return -EPERM;
> + }
>
> return simple_unlink(dir, dentry);
> }
> --
> 2.9.3
>
--
Kees Cook
Nexus Security
