From d1dc72a52e00e9c8816cc50c952202c643424ee6 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Tue, 15 Jun 2021 20:33:38 -0700 Subject: [PATCH] ethtool: add a stricter length check There has been a few errors in the ethtool reply size calculations, most of those are hard to trigger during basic testing because of skb size rounding up and netdev names being shorter than max. Add a more precise check. This change will affect the value of payload length displayed in case of -EMSGSIZE but that should be okay, "payload length" isn't a well defined term here. Signed-off-by: Jakub Kicinski Signed-off-by: David S. Miller Signed-off-by: hongrongxuan --- net/ethtool/netlink.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c index c5b377ded213..b36b2ebcb22f 100644 --- a/net/ethtool/netlink.c +++ b/net/ethtool/netlink.c @@ -305,9 +305,9 @@ static int ethnl_default_doit(struct sk_buff *skb, struct genl_info *info) struct ethnl_req_info *req_info = NULL; const u8 cmd = info->genlhdr->cmd; const struct ethnl_request_ops *ops; + int hdr_len, reply_len; struct sk_buff *rskb; void *reply_payload; - int reply_len; int ret; ops = ethnl_default_requests[cmd]; @@ -336,15 +336,20 @@ static int ethnl_default_doit(struct sk_buff *skb, struct genl_info *info) ret = ops->reply_size(req_info, reply_data); if (ret < 0) goto err_cleanup; - reply_len = ret + ethnl_reply_header_size(); + reply_len = ret; ret = -ENOMEM; - rskb = ethnl_reply_init(reply_len, req_info->dev, ops->reply_cmd, + rskb = ethnl_reply_init(reply_len + ethnl_reply_header_size(), + req_info->dev, ops->reply_cmd, ops->hdr_attr, info, &reply_payload); if (!rskb) goto err_cleanup; + hdr_len = rskb->len; ret = ops->fill_reply(rskb, req_info, reply_data); if (ret < 0) goto err_msg; + WARN_ONCE(rskb->len - hdr_len > reply_len, + "ethnl cmd %d: calculated reply length %d, but consumed %d\n", + cmd, reply_len, rskb->len - hdr_len); if (ops->cleanup_data) ops->cleanup_data(reply_data);