[Xen-devel] [PATCH 1/1] xen-netfront: do not cast grant table reference to signed short

[Dongli Zhang <dongli.zhang@xxxxxxxxxx>]

While grant reference is of type uint32_t, xen-netfront erroneously casts
it to signed short in BUG_ON().

This would lead to the xen domU panic during boot-up or migration when it
is attached with lots of paravirtual devices.

Signed-off-by: Dongli Zhang <dongli.zhang@xxxxxxxxxx>
---
 drivers/net/xen-netfront.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index e17879d..189a28d 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -304,7 +304,7 @@ static void xennet_alloc_rx_buffers(struct netfront_queue 
*queue)
                queue->rx_skbs[id] = skb;
 
                ref = gnttab_claim_grant_reference(&queue->gref_rx_head);
-               BUG_ON((signed short)ref < 0);
+               WARN_ON_ONCE(IS_ERR_VALUE((unsigned long)ref));
                queue->grant_rx_ref[id] = ref;
 
                page = skb_frag_page(&skb_shinfo(skb)->frags[0]);
@@ -428,7 +428,7 @@ static void xennet_tx_setup_grant(unsigned long gfn, 
unsigned int offset,
        id = get_id_from_freelist(&queue->tx_skb_freelist, queue->tx_skbs);
        tx = RING_GET_REQUEST(&queue->tx, queue->tx.req_prod_pvt++);
        ref = gnttab_claim_grant_reference(&queue->gref_tx_head);
-       BUG_ON((signed short)ref < 0);
+       WARN_ON_ONCE(IS_ERR_VALUE((unsigned long)ref));
 
        gnttab_grant_foreign_access_ref(ref, queue->info->xbdev->otherend_id,
                                        gfn, GNTMAP_readonly);
-- 
2.7.4


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