From: Kees Cook <keescook@chromium.org>
To: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] net: print proper warning on dst underflow
Date: Wed, 13 Nov 2019 16:31:40 -0800 [thread overview]
Message-ID: <201911131625.8B0F0BAEDE@keescook> (raw)
In-Reply-To: <20190924090937.13001-1-Jason@zx2c4.com>
On Tue, Sep 24, 2019 at 11:09:37AM +0200, Jason A. Donenfeld wrote:
> Proper warnings with stack traces make it much easier to figure out
> what's doing the double free and create more meaningful bug reports from
> users.
>
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> ---
> net/core/dst.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/net/core/dst.c b/net/core/dst.c
> index 1325316d9eab..193af526e908 100644
> --- a/net/core/dst.c
> +++ b/net/core/dst.c
> @@ -172,7 +172,7 @@ void dst_release(struct dst_entry *dst)
> int newrefcnt;
>
> newrefcnt = atomic_dec_return(&dst->__refcnt);
> - if (unlikely(newrefcnt < 0))
> + if (WARN_ONCE(newrefcnt < 0, "dst_release underflow"))
> net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
> __func__, dst, newrefcnt);
Should __refcnt be a refcount_t to gain saturation protection? It seems
like going negative is bad...
-Kees
> if (!newrefcnt)
> @@ -187,7 +187,7 @@ void dst_release_immediate(struct dst_entry *dst)
> int newrefcnt;
>
> newrefcnt = atomic_dec_return(&dst->__refcnt);
> - if (unlikely(newrefcnt < 0))
> + if (WARN_ONCE(newrefcnt < 0, "dst_release_immediate underflow"))
> net_warn_ratelimited("%s: dst:%p refcnt:%d\n",
> __func__, dst, newrefcnt);
> if (!newrefcnt)
> --
> 2.21.0
>
--
Kees Cook
prev parent reply other threads:[~2019-11-14 0:31 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-24 9:09 [PATCH] net: print proper warning on dst underflow Jason A. Donenfeld
2019-09-26 7:06 ` David Miller
2019-11-14 0:31 ` Kees Cook [this message]
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