From: Dan Carpenter Date: Thu, 17 May 2018 12:33:36 +0000 Subject: [PATCH] net/ncsi: prevent a couple array underflows Message-Id: <20180517123336.GB7655@mwanda> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: "David S. Miller" , Samuel Mendoza-Jonas Cc: netdev@vger.kernel.org, Gavin Shan , kernel-janitors@vger.kernel.org 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 diff --git a/net/ncsi/ncsi-rsp.c b/net/ncsi/ncsi-rsp.c index ce9497966ebe..a6b7c7d5c829 100644 --- a/net/ncsi/ncsi-rsp.c +++ b/net/ncsi/ncsi-rsp.c @@ -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;