Hello Pavel, On Mon, Oct 07, 2024 at 05:48:39PM +0100, Pavel Begunkov wrote: > On 10/7/24 17:20, Breno Leitao wrote: > > On Sat, Oct 05, 2024 at 01:38:59PM +0900, Akinobu Mita wrote: > > > 2024年10月2日(水) 20:37 Breno Leitao <leitao@xxxxxxxxxx>: > > > > > > > > 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@xxxxxxxxxx/ > > > > > > > > CC: Akinobu Mita <akinobu.mita@xxxxxxxxx> > > > > Suggested-by: Jakub Kicinski <kuba@xxxxxxxxxx> > > > > Signed-off-by: Breno Leitao <leitao@xxxxxxxxxx> > > > > > > This new addition seems sensible. It might be more useful to have a filter > > > that allows you to specify things like protocol family. > > > > I think it might make more sense to be network interface specific. For > > instance, only fault inject in interface `ethx`. > > Wasn't there some error injection infra that allows to optionally > run bpf? That would cover the filtering problem. ALLOW_ERROR_INJECTION, > maybe? Isn't ALLOW_ERROR_INJECTION focused on specifying which function could be faulted? I.e, you can mark that function as prone for fail injection? In my the case I have in mind, I want to pass the interface that it would have the error injected. For instance, only inject errors in interface eth1. In this case, I am not sure ALLOW_ERROR_INJECTION will help. Thanks --breno
