[Xen-changelog] [linux-2.6.18-xen] netfront: don't truncate grant references

[Xen patchbot-linux-2.6.18-xen <patchbot@xxxxxxx>]

# HG changeset patch
# User Jan Beulich <jbeulich@xxxxxxxx>
# Date 1478188314 -3600
#      Thu Nov 03 16:51:54 2016 +0100
# Node ID 87faef7f0177ac77227628d430c8c7c7e2444dae
# Parent  896b47a37cf83c7d204ee2196b8135eeee1dff9d
netfront: don't truncate grant references

They're of type uint32_t, and hence error checks must not use a more
narrow type.

Reported-by: Dongli Zhang <dongli.zhang@xxxxxxxxxx>
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---


diff -r 896b47a37cf8 -r 87faef7f0177 drivers/xen/netfront/netfront.c
--- a/drivers/xen/netfront/netfront.c   Fri Oct 07 12:05:15 2016 +0200
+++ b/drivers/xen/netfront/netfront.c   Thu Nov 03 16:51:54 2016 +0100
@@ -798,7 +798,7 @@ no_skb:
                np->rx_skbs[id] = skb;
 
                ref = gnttab_claim_grant_reference(&np->gref_rx_head);
-               BUG_ON((signed short)ref < 0);
+               BUG_ON(IS_ERR_VALUE((int32_t)ref));
                np->grant_rx_ref[id] = ref;
 
                pfn = page_to_pfn(skb_shinfo(skb)->frags[0].page);
@@ -905,7 +905,7 @@ static void xennet_make_frags(struct sk_
                tx = RING_GET_REQUEST(&np->tx, prod++);
                tx->id = id;
                ref = gnttab_claim_grant_reference(&np->gref_tx_head);
-               BUG_ON((signed short)ref < 0);
+               BUG_ON(IS_ERR_VALUE((int32_t)ref));
 
                mfn = virt_to_mfn(data);
                gnttab_grant_foreign_access_ref(ref, np->xbdev->otherend_id,
@@ -927,7 +927,7 @@ static void xennet_make_frags(struct sk_
                tx = RING_GET_REQUEST(&np->tx, prod++);
                tx->id = id;
                ref = gnttab_claim_grant_reference(&np->gref_tx_head);
-               BUG_ON((signed short)ref < 0);
+               BUG_ON(IS_ERR_VALUE((int32_t)ref));
 
                mfn = pfn_to_mfn(page_to_pfn(frag->page));
                gnttab_grant_foreign_access_ref(ref, np->xbdev->otherend_id,
@@ -1000,7 +1000,7 @@ static int network_start_xmit(struct sk_
 
        tx->id   = id;
        ref = gnttab_claim_grant_reference(&np->gref_tx_head);
-       BUG_ON((signed short)ref < 0);
+       BUG_ON(IS_ERR_VALUE((int32_t)ref));
        mfn = virt_to_mfn(data);
        gnttab_grant_foreign_access_ref(
                ref, np->xbdev->otherend_id, mfn, GTF_readonly);

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