Date: Fri, 12 Jan 2018 10:47:44 -0800 From: Dan Williams <dan.j.williams@...el.com> To: Greg KH <gregkh@...uxfoundation.org> Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, linux-arch@...r.kernel.org, Andrew Morton <akpm@...ux-foundation.org>, kernel-hardening@...ts.openwall.com, Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>, Netdev <netdev@...r.kernel.org>, Alexey Kuznetsov <kuznet@....inr.ac.ru>, Thomas Gleixner <tglx@...utronix.de>, Linus Torvalds <torvalds@...ux-foundation.org>, "David S. Miller" <davem@...emloft.net>, Elena Reshetova <elena.reshetova@...el.com>, Alan Cox <alan@...ux.intel.com> Subject: Re: [PATCH v2 10/19] ipv4: prevent bounds-check bypass via speculative execution On Thu, Jan 11, 2018 at 11:59 PM, Greg KH <gregkh@...uxfoundation.org> wrote: > On Thu, Jan 11, 2018 at 04:47:18PM -0800, Dan Williams wrote: >> Static analysis reports that 'offset' may be a user controlled value >> that is used as a data dependency reading from a raw_frag_vec buffer. >> In order to avoid potential leaks of kernel memory values, block >> speculative execution of the instruction stream that could issue further >> reads based on an invalid '*(rfv->c + offset)' value. >> >> Based on an original patch by Elena Reshetova. > > There is the "Co-Developed-by:" tag now, if you want to use it... Ok, thanks. > >> Cc: "David S. Miller" <davem@...emloft.net> >> Cc: Alexey Kuznetsov <kuznet@....inr.ac.ru> >> Cc: Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org> >> Cc: netdev@...r.kernel.org >> Signed-off-by: Elena Reshetova <elena.reshetova@...el.com> >> Signed-off-by: Dan Williams <dan.j.williams@...el.com> >> --- >> net/ipv4/raw.c | 10 ++++++---- >> 1 file changed, 6 insertions(+), 4 deletions(-) > > Ugh, what is this, the 4th time I've said "I don't think this is an > issue, so why are you changing this code." to this patch. To be > followed by a "oh yeah, you are right, I'll drop it", only to see it > show back up in the next time this patch series is sent out? > > Same for the other patches in this series that I have reviewed 4, maybe > 5, times already. The "v2" is not very true here... The theme of the review feedback on v1 was 'don't put ifence in any net/ code', and that was addressed. I honestly thought the new definition of array_ptr() changed the calculus on this patch. Given the same pattern appears in the ipv6 case, and I have yet to hear that we should drop the ipv6 patch, make the code symmetric just for readability purposes. Otherwise we need a comment saying why this is safe for ipv4, but maybe not safe for ipv6, I think 'array_ptr' is effectively that comment. I.e. 'array_ptr()' is designed to be low impact for instrumenting false positives. If that new argument does not hold water I will definitely drop this patch.
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