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net/ncsi: prevent a couple array underflows
authorDan Carpenter <dan.carpenter@oracle.com>
Thu, 17 May 2018 12:33:36 +0000 (15:33 +0300)
committerDavid S. Miller <davem@davemloft.net>
Thu, 17 May 2018 20:27:39 +0000 (16:27 -0400)
We recently refactored this code and introduced a static checker
warning.  Smatch complains that if cmd->index is zero then we would
underflow the arrays.  That's obviously true.

The question is whether we prevent cmd->index from being zero at a
different level.  I've looked at the code and I don't immediately see
a check for that.

Fixes: 062b3e1b6d4f ("net/ncsi: Refactor MAC, VLAN filters")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/ncsi/ncsi-rsp.c

index ce94979..a6b7c7d 100644 (file)
@@ -347,7 +347,7 @@ static int ncsi_rsp_handler_svf(struct ncsi_request *nr)
 
        cmd = (struct ncsi_cmd_svf_pkt *)skb_network_header(nr->cmd);
        ncf = &nc->vlan_filter;
-       if (cmd->index > ncf->n_vids)
+       if (cmd->index == 0 || cmd->index > ncf->n_vids)
                return -ERANGE;
 
        /* Add or remove the VLAN filter. Remember HW indexes from 1 */
@@ -445,7 +445,8 @@ static int ncsi_rsp_handler_sma(struct ncsi_request *nr)
        ncf = &nc->mac_filter;
        bitmap = &ncf->bitmap;
 
-       if (cmd->index > ncf->n_uc + ncf->n_mc + ncf->n_mixed)
+       if (cmd->index == 0 ||
+           cmd->index > ncf->n_uc + ncf->n_mc + ncf->n_mixed)
                return -ERANGE;
 
        index = (cmd->index - 1) * ETH_ALEN;