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From: Andrew Morton <akpm@linux-foundation.org>
To: Maxime COQUELIN <maxime.coquelin@st.com>
Cc: linux@rasmusvillemoes.dk, gong.chen@linux.intel.com,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>,
	" Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	tytso@mit.edu, linux-kernel@vger.kernel.org,
	stable@vger.kernel.org, kernel@stlinux.com, eric.paire@st.com
Subject: Re: [PATCH v4] bitops: Fix shift overflow in GENMASK macros
Date: Thu, 13 Nov 2014 14:09:36 -0800	[thread overview]
Message-ID: <20141113140936.e2e45a8970b5bb4195fd5065@linux-foundation.org> (raw)
In-Reply-To: <1415267659-10563-1-git-send-email-maxime.coquelin@st.com>

On Thu,  6 Nov 2014 10:54:19 +0100 Maxime COQUELIN <maxime.coquelin@st.com> wrote:

> On some 32 bits architectures, including x86, GENMASK(31, 0) returns 0
> instead of the expected ~0UL.
> 
> This is the same on some 64 bits architectures with GENMASK_ULL(63, 0).
> 
> This is due to an overflow in the shift operand, 1 << 32 for GENMASK,
> 1 << 64 for GENMASK_ULL.
> 
> Fixes: 10ef6b0dffe404bcc54e94cb2ca1a5b18445a66b
> Cc: <stable@vger.kernel.org> #v3.13+
> Reported-by: Eric Paire <eric.paire@st.com>
> Suggested-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> Signed-off-by: Maxime Coquelin <maxime.coquelin@st.com>

Why cc:stable?  Does this bug cause some observed kernel misbehaviour? 
If so, please fully describe that in the changelog.  This will help
people to determine whether this patch might fix a bug they're
observing, and will help them to decide whether they should backport
this patch into their kernels.

I'm assuming that Peter will be merging this patch.


  reply	other threads:[~2014-11-13 22:09 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-11-06  9:54 Maxime COQUELIN
2014-11-13 22:09 ` Andrew Morton [this message]
2014-11-14 14:07   ` Maxime Coquelin
2014-11-14 20:03     ` Max Filippov
2014-11-16  9:49 ` [tip:core/urgent] " tip-bot for Maxime COQUELIN

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