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Date: Fri, 22 Nov 2019 22:56:05 -0800 From: John Fastabend <john.fastabend@...il.com> To: Jakub Kicinski <jakub.kicinski@...ronome.com>, john.fastabend@...il.com, daniel@...earbox.net Cc: borisp@...lanox.com, aviadye@...lanox.com, netdev@...r.kernel.org, syzbot+df0d4ec12332661dd1f9@...kaller.appspotmail.com Subject: Re: [RFC net] net/tls: clear SG markings on encryption error Jakub Kicinski wrote: > On Fri, 22 Nov 2019 13:45:53 -0800, Jakub Kicinski wrote: > > Also there's at least one more bug in this piece of code, TLS 1.3 > > can't assume there's at least one free SG entry. > > And I don't see any place where the front and back of the SG circular > buffer are actually chained :( This: The easiest way to generate a message that needs to be chained is to use cork but we haven't yet enabled cork. However, there is one case with the use of apply, pass, and drop that I think this case could also be generated. I'll add a test for it and a fix. This case should only be hit when using with BPF and programs using apply/cork. I have the patches for cork support on a branch as well so we should probably just send those out. > > static inline void sk_msg_init(struct sk_msg *msg) > { > BUILD_BUG_ON(ARRAY_SIZE(msg->sg.data) - 1 != MAX_MSG_FRAGS); > memset(msg, 0, sizeof(*msg)); > sg_init_marker(msg->sg.data, MAX_MSG_FRAGS); > } > > looks questionable as well, we shouldn't mark MAX_MSG_FRAGS as the end, > we don't know where the end is going to be.. We use end->MAX_MSG_FRAGS and size==0 to indicate an fresh sk_msg. This should only ever be called to initialize a msg never afterwards. > > diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h > index 6cb077b646a5..6c6ce6f90e7d 100644 > --- a/include/linux/skmsg.h > +++ b/include/linux/skmsg.h > @@ -173,9 +173,8 @@ static inline void sk_msg_clear_meta(struct sk_msg *msg) > > static inline void sk_msg_init(struct sk_msg *msg) > { > - BUILD_BUG_ON(ARRAY_SIZE(msg->sg.data) - 1 != MAX_MSG_FRAGS); > memset(msg, 0, sizeof(*msg)); > - sg_init_marker(msg->sg.data, MAX_MSG_FRAGS); > + sg_chain(msg->sg.data, ARRAY_SIZE(msg->sg.data), msg->sg.data); > } > I don't think we want to chain these here. We could drop the init marker part but its handy when reading sg values. > static inline void sk_msg_xfer(struct sk_msg *dst, struct sk_msg *src, > > Hm? Nice catch on the missing chaining we dropped across various revisions and rebases of the code. Without cork support our test cases don't hit it now.
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