From: Kees Cook <keescook@chromium.org>
To: Dean Luick <dean.luick@cornelisnetworks.com>
Cc: Leon Romanovsky <leon@kernel.org>,
Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>,
Jason Gunthorpe <jgg@ziepe.ca>,
Justin Stitt <justinstitt@google.com>,
linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-hardening@vger.kernel.org
Subject: Re: [PATCH] IB/hfi1: replace deprecated strncpy
Date: Sat, 23 Sep 2023 20:20:54 -0700 [thread overview]
Message-ID: <202309232019.BE78A9C0@keescook> (raw)
In-Reply-To: <2f4bd46c-664e-4253-8d57-16bd46dd3be8@cornelisnetworks.com>
On Fri, Sep 22, 2023 at 09:25:39AM -0500, Dean Luick wrote:
> On 9/22/2023 5:29 AM, Leon Romanovsky wrote:
> >
> > On Thu, 21 Sep 2023 07:17:47 +0000, Justin Stitt wrote:
> >> `strncpy` is deprecated for use on NUL-terminated destination strings
> >> [1] and as such we should prefer more robust and less ambiguous string
> >> interfaces.
> >>
> >> We see that `buf` is expected to be NUL-terminated based on it's use
> >> within a trace event wherein `is_misc_err_name` and `is_various_name`
> >> map to `is_name` through `is_table`:
> >> | TRACE_EVENT(hfi1_interrupt,
> >> | TP_PROTO(struct hfi1_devdata *dd, const struct is_table *is_entry,
> >> | int src),
> >> | TP_ARGS(dd, is_entry, src),
> >> | TP_STRUCT__entry(DD_DEV_ENTRY(dd)
> >> | __array(char, buf, 64)
> >> | __field(int, src)
> >> | ),
> >> | TP_fast_assign(DD_DEV_ASSIGN(dd);
> >> | is_entry->is_name(__entry->buf, 64,
> >> | src - is_entry->start);
> >> | __entry->src = src;
> >> | ),
> >> | TP_printk("[%s] source: %s [%d]", __get_str(dev), __entry->buf,
> >> | __entry->src)
> >> | );
> >>
> >> [...]
> >
> > Applied, thanks!
>
> It is unfortunate that this and the qib patch was accepted so quickly. The replacement is functionally correct. However, I was going to suggest using strscpy() since the return value is never looked at and all use cases only require a NUL-terminated string. Padding is not needed.
Is the trace buffer already guaranteed to be zeroed? Since this is
defined as a fixed-size string in the buffer, it made sense to me to be
sure that the unused bytes were 0 before copying them to userspace.
-Kees
>
> >
> > [1/1] IB/hfi1: replace deprecated strncpy
> > https://git.kernel.org/rdma/rdma/c/c2d0c5b28a77d5
> >
> > Best regards,
>
> External recipient
--
Kees Cook
next prev parent reply other threads:[~2023-09-24 3:21 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-21 7:17 [PATCH] IB/hfi1: replace deprecated strncpy Justin Stitt
2023-09-22 10:29 ` Leon Romanovsky
2023-09-22 14:25 ` Dean Luick
2023-09-24 3:20 ` Kees Cook [this message]
2023-09-26 12:56 ` Dean Luick
2023-09-29 19:56 ` Kees Cook
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