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authorJakub Kicinski <kuba@kernel.org>2021-06-15 20:33:38 -0700
committerDavid S. Miller <davem@davemloft.net>2021-06-16 00:40:44 -0700
commit4d1fb7cde0ccc6000cafb72d9079de1504e3cb2a (patch)
treed8c02b3d72f4e50d6f9ccc42f381bb075944cf66 /net/ethtool
parent1b3fc771769c9f9418b23dd5676ab25a215d247d (diff)
downloadlinux-4d1fb7cde0ccc6000cafb72d9079de1504e3cb2a.tar.bz2
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 <kuba@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ethtool')
-rw-r--r--net/ethtool/netlink.c11
1 files changed, 8 insertions, 3 deletions
diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c
index 88d8a0243f35..a7346346114f 100644
--- a/net/ethtool/netlink.c
+++ b/net/ethtool/netlink.c
@@ -315,9 +315,9 @@ 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];
@@ -346,15 +346,20 @@ 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);