Messages in this thread |  | | Date | Mon, 26 Jul 2021 14:30:44 -0700 (PDT) | From | Stefano Stabellini <> | Subject | Re: [PATCH] 9p/xen: Fix end of loop tests for list_for_each_entry |
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On Mon, 26 Jul 2021, asmadeus@codewreck.org wrote: > Harshvardhan Jha wrote on Sun, Jul 25, 2021 at 11:21:03PM +0530: > > The list_for_each_entry() iterator, "priv" in this code, can never be > > NULL so the warning would never be printed. > > hm? priv won't be NULL but priv->client won't be client, so it will > return -EINVAL alright in practice? > > This does fix an invalid read after the list head, so there's a real > bug, but the commit message needs fixing.
Agreed
> > Signed-off-by: Harshvardhan Jha <harshvardhan.jha@oracle.com> > > --- > > From static analysis. Not tested. > > +Stefano in To - I also can't test xen right now :/ > This looks functional to me but if you have a bit of time to spare just > a mount test can't hurt.
Yes, I did test it successfully. Aside from the commit messaged to be reworded:
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Tested-by: Stefano Stabellini <sstabellini@kernel.org>
> > --- > > net/9p/trans_xen.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c > > index f4fea28e05da..3ec1a51a6944 100644 > > --- a/net/9p/trans_xen.c > > +++ b/net/9p/trans_xen.c > > @@ -138,7 +138,7 @@ static bool p9_xen_write_todo(struct xen_9pfs_dataring *ring, RING_IDX size) > > > > static int p9_xen_request(struct p9_client *client, struct p9_req_t *p9_req) > > { > > - struct xen_9pfs_front_priv *priv = NULL; > > + struct xen_9pfs_front_priv *priv; > > RING_IDX cons, prod, masked_cons, masked_prod; > > unsigned long flags; > > u32 size = p9_req->tc.size; > > @@ -151,7 +151,7 @@ static int p9_xen_request(struct p9_client *client, struct p9_req_t *p9_req) > > break; > > } > > read_unlock(&xen_9pfs_lock); > > - if (!priv || priv->client != client) > > + if (list_entry_is_head(priv, &xen_9pfs_devs, list)) > > return -EINVAL; > > > > num = p9_req->tc.tag % priv->num_rings;
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