Messages in this thread |  | | Date | Mon, 26 Jul 2021 05:46:33 +0900 | From | asmadeus@codewrec ... | Subject | Re: [PATCH] 9p/xen: Fix end of loop tests for list_for_each_entry |
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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.
> > 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.
> --- > 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; -- Dominique
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