linux-kernel - Re: [PATCH net-next] net: Implement fault injection forcing skb reallocation

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Message-ID: <CAC5umyjkmkY4111CG_ODK6s=rcxT_HHAQisOiwRp5de0KJkzBA@mail.gmail.com>
Date: Sat, 5 Oct 2024 13:38:59 +0900
From: Akinobu Mita <akinobu.mita@...il.com>
To: Breno Leitao <leitao@...ian.org>
Cc: kuba@...nel.org, davem@...emloft.net, edumazet@...gle.com, 
	pabeni@...hat.com, Jonathan Corbet <corbet@....net>, horms@...nel.org, 
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Mina Almasry <almasrymina@...gle.com>, Pavel Begunkov <asml.silence@...il.com>, 
	Willem de Bruijn <willemb@...gle.com>, Alexander Lobakin <aleksander.lobakin@...el.com>, 
	"open list:DOCUMENTATION" <linux-doc@...r.kernel.org>
Subject: Re: [PATCH net-next] net: Implement fault injection forcing skb reallocation

2024年10月2日(水) 20:37 Breno Leitao <leitao@...ian.org>:
>
> Introduce a fault injection mechanism to force skb reallocation. The
> primary goal is to catch bugs related to pointer invalidation after
> potential skb reallocation.
>
> The fault injection mechanism aims to identify scenarios where callers
> retain pointers to various headers in the skb but fail to reload these
> pointers after calling a function that may reallocate the data. This
> type of bug can lead to memory corruption or crashes if the old,
> now-invalid pointers are used.
>
> By forcing reallocation through fault injection, we can stress-test code
> paths and ensure proper pointer management after potential skb
> reallocations.
>
> Add a hook for fault injection in the following functions:
>
>  * pskb_trim_rcsum()
>  * pskb_may_pull_reason()
>  * pskb_trim()
>
> As the other fault injection mechanism, protect it under a debug Kconfig
> called CONFIG_FAIL_SKB_FORCE_REALLOC.
>
> This patch was *heavily* inspired by Jakub's proposal from:
> https://lore.kernel.org/all/20240719174140.47a868e6@kernel.org/
>
> CC: Akinobu Mita <akinobu.mita@...il.com>
> Suggested-by: Jakub Kicinski <kuba@...nel.org>
> Signed-off-by: Breno Leitao <leitao@...ian.org>

This new addition seems sensible.  It might be more useful to have a filter
that allows you to specify things like protocol family.