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* [PATCH net-next] ethtool: add a stricter length check
@ 2021-06-16  3:33 Jakub Kicinski
  2021-06-16  7:50 ` patchwork-bot+netdevbpf
  0 siblings, 1 reply; 2+ messages in thread
From: Jakub Kicinski @ 2021-06-16  3:33 UTC (permalink / raw)
  To: davem; +Cc: netdev, mkubecek, Jakub Kicinski

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>
---
 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 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);
 
-- 
2.31.1


^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH net-next] ethtool: add a stricter length check
  2021-06-16  3:33 [PATCH net-next] ethtool: add a stricter length check Jakub Kicinski
@ 2021-06-16  7:50 ` patchwork-bot+netdevbpf
  0 siblings, 0 replies; 2+ messages in thread
From: patchwork-bot+netdevbpf @ 2021-06-16  7:50 UTC (permalink / raw)
  To: Jakub Kicinski; +Cc: davem, netdev, mkubecek

Hello:

This patch was applied to netdev/net-next.git (refs/heads/master):

On Tue, 15 Jun 2021 20:33:38 -0700 you wrote:
> 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.
> 
> [...]

Here is the summary with links:
  - [net-next] ethtool: add a stricter length check
    https://git.kernel.org/netdev/net-next/c/4d1fb7cde0cc

You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html



^ permalink raw reply	[flat|nested] 2+ messages in thread

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2021-06-16  7:50 ` patchwork-bot+netdevbpf

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