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SubjectRe: [PATCH] nfsd: fix NULL dereference in nfsd_statfs()
On Fri, Aug 13, 2010 at 03:53:49PM +0200, Takashi Iwai wrote:
> The commit ebabe9a9001af0af56c0c2780ca1576246e7a74b
> pass a struct path to vfs_statfs
> introduced the struct path initialization, and this seems to trigger
> an Oops on my machine.
>
> fh_dentry field may be NULL and set later in fh_verify(), thus the
> initialization of path must be after fh_verify().

Thanks, the patch looks good.


Reviewed-by: Christoph Hellwig <hch@lst.de>

> diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
> index 96360a8..661a6cf 100644
> --- a/fs/nfsd/vfs.c
> +++ b/fs/nfsd/vfs.c
> @@ -2033,15 +2033,17 @@ out:
> __be32
> nfsd_statfs(struct svc_rqst *rqstp, struct svc_fh *fhp, struct kstatfs *stat, int access)
> {
> - struct path path = {
> - .mnt = fhp->fh_export->ex_path.mnt,
> - .dentry = fhp->fh_dentry,
> - };
> __be32 err;
>
> err = fh_verify(rqstp, fhp, 0, NFSD_MAY_NOP | access);
> - if (!err && vfs_statfs(&path, stat))
> - err = nfserr_io;
> + if (!err) {
> + struct path path = {
> + .mnt = fhp->fh_export->ex_path.mnt,
> + .dentry = fhp->fh_dentry,
> + };
> + if (vfs_statfs(&path, stat))
> + err = nfserr_io;
> + }
> return err;
> }
>
> --
> 1.7.2.1
---end quoted text---


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