Re: [PATCH] Fix mountpoint reference leakage in linkat

From: Al Viro
Date: Fri Jan 31 2014 - 16:03:42 EST


On Fri, Jan 31, 2014 at 03:41:58PM -0500, Oleg Drokin wrote:
> Recent changes to retry on ESTALE in linkat
> (commit 442e31ca5a49e398351b2954b51f578353fdf210)
> introduced a mountpoint reference leak and a small memory
> leak in case a filesystem link operation returns ESTALE
> which is pretty normal for distributed filesystems like
> lustre, nfs and so on.
> Free old_path in such a case.
>
> Signed-off-by: Oleg Drokin: <green@xxxxxxxxxxxxxx>
> ---
> fs/namei.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/fs/namei.c b/fs/namei.c
> index bcb838e..e620937 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -3931,6 +3931,7 @@ out_dput:
> goto retry;
> }
> if (retry_estale(error, how)) {
> + path_put(&old_path);
> how |= LOOKUP_REVAL;
> goto retry;
> }

Umm... That obviously can't be right - we have another goto retry
in the same situation (see in your diff context). I agree that
we have a leak there, but you've fixed only a half of it.
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