diff options
| author | Ross Lagerwall <ross.lagerwall@citrix.com> | 2023-08-03 08:41:22 +0200 |
|---|---|---|
| committer | Juergen Gross <jgross@suse.com> | 2023-08-03 09:04:08 +0200 |
| commit | 534fc31d09b706a16d83533e16b5dc855caf7576 (patch) | |
| tree | 78f0abcc04ca238f4b6598737ed79bf476d4832b /drivers/net/xen-netback | |
| parent | ec351c8f2e6211054e51e661589cddd1fe856425 (diff) | |
xen/netback: Fix buffer overrun triggered by unusual packet
It is possible that a guest can send a packet that contains a head + 18
slots and yet has a len <= XEN_NETBACK_TX_COPY_LEN. This causes nr_slots
to underflow in xenvif_get_requests() which then causes the subsequent
loop's termination condition to be wrong, causing a buffer overrun of
queue->tx_map_ops.
Rework the code to account for the extra frag_overflow slots.
This is CVE-2023-34319 / XSA-432.
Fixes: ad7f402ae4f4 ("xen/netback: Ensure protocol headers don't fall in the non-linear area")
Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Reviewed-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Juergen Gross <jgross@suse.com>
Diffstat (limited to 'drivers/net/xen-netback')
| -rw-r--r-- | drivers/net/xen-netback/netback.c | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index c8d20cddf658..88f760a7cbc3 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -396,7 +396,7 @@ static void xenvif_get_requests(struct xenvif_queue *queue, struct gnttab_map_grant_ref *gop = queue->tx_map_ops + *map_ops; struct xen_netif_tx_request *txp = first; - nr_slots = shinfo->nr_frags + 1; + nr_slots = shinfo->nr_frags + frag_overflow + 1; copy_count(skb) = 0; XENVIF_TX_CB(skb)->split_mask = 0; @@ -462,8 +462,8 @@ static void xenvif_get_requests(struct xenvif_queue *queue, } } - for (shinfo->nr_frags = 0; shinfo->nr_frags < nr_slots; - shinfo->nr_frags++, gop++) { + for (shinfo->nr_frags = 0; nr_slots > 0 && shinfo->nr_frags < MAX_SKB_FRAGS; + shinfo->nr_frags++, gop++, nr_slots--) { index = pending_index(queue->pending_cons++); pending_idx = queue->pending_ring[index]; xenvif_tx_create_map_op(queue, pending_idx, txp, @@ -476,12 +476,12 @@ static void xenvif_get_requests(struct xenvif_queue *queue, txp++; } - if (frag_overflow) { + if (nr_slots > 0) { shinfo = skb_shinfo(nskb); frags = shinfo->frags; - for (shinfo->nr_frags = 0; shinfo->nr_frags < frag_overflow; + for (shinfo->nr_frags = 0; shinfo->nr_frags < nr_slots; shinfo->nr_frags++, txp++, gop++) { index = pending_index(queue->pending_cons++); pending_idx = queue->pending_ring[index]; @@ -492,6 +492,11 @@ static void xenvif_get_requests(struct xenvif_queue *queue, } skb_shinfo(skb)->frag_list = nskb; + } else if (nskb) { + /* A frag_list skb was allocated but it is no longer needed + * because enough slots were converted to copy ops above. + */ + kfree_skb(nskb); } (*copy_ops) = cop - queue->tx_copy_ops; |