On 10/12/19 7:51 AM, Markus Elfring wrote:
> Hello,
>
> I tried another script for the semantic patch language out.
> This source code analysis approach points out that the implementation
> of the function “tcp_time_wait” contains also a call of the function
> “kmemdup”.
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/net/ipv4/tcp_minisocks.c?id=1c0cc5f1ae5ee5a6913704c0d75a6e99604ee30a#n306
> https://elixir.bootlin.com/linux/v5.4-rc2/source/net/ipv4/tcp_minisocks.c#L306
>
> * Do you find the usage of the macro call “BUG_ON” still appropriate at this
> place?
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/checkpatch.pl?id=1c0cc5f1ae5ee5a6913704c0d75a6e99604ee30a#n4080
>
> * Is there a need to adjust the error handling here?
Presumably the BUG would trigger if a really disturbing bug happened.
There is no chance a timewait socket could be created with a MD5 key,
if the established socket that is the 'parent' of the timewait
has not a MD5 context itself.
The parent socket only could have MD5 context if tcp_md5sig_pool_populated
could have been set to true.
Once tcp_md5sig_pool_populated is true it can never go back to false.
So the bug here would be that a socket had a successful MD5 context,
and following tcp_alloc_md5sig_pool() would return false.
We can discuss of all BUG() in general, some people simply disable
all of them (cf CONFIG_BUG), but this particular one does not seem
specially bad to me, compared to others.
