From: Al Viro <viro@zeniv.linux.org.uk>
To: Zhen Lei <thunder.leizhen@huawei.com>
Cc: Eric Biggers <ebiggers@kernel.org>,
linux-fsdevel@vger.kernel.org, Chris Mason <clm@fb.com>,
Josef Bacik <josef@toxicpanda.com>,
David Sterba <dsterba@suse.com>,
linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 0/2] fs: clear a UBSAN shift-out-of-bounds warning
Date: Fri, 25 Nov 2022 21:00:17 +0000 [thread overview]
Message-ID: <Y4Es4TIbVos5CTO9@ZenIV> (raw)
In-Reply-To: <20221125091358.1963-1-thunder.leizhen@huawei.com>
On Fri, Nov 25, 2022 at 05:13:56PM +0800, Zhen Lei wrote:
> v2 --> v3:
> Updated the commit message of patch 2/2 based on Alexander Viro's suggestion.
Not exactly what I meant... I've tentatively applied it, with the
following commit message:
--------------------------------
get rid of INT_LIMIT, use type_max() instead
INT_LIMIT() tries to do what type_max() does, except that type_max()
doesn't rely upon undefined behaviour[*], might as well use type_max()
instead.
[*] if T is an N-bit signed integer type, the maximal value in T is
pow(2, N - 1) - 1, all right, but naive expression for that value
ends up with a couple of wraparounds and as usual for wraparounds
in signed types, that's an undefined behaviour. type_max() takes
care to avoid those...
Caught-by: UBSAN
Suggested-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
--------------------------------
Does anybody have objections against the commit message above?
next prev parent reply other threads:[~2022-11-25 21:00 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-25 9:13 [PATCH v3 0/2] fs: clear a UBSAN shift-out-of-bounds warning Zhen Lei
2022-11-25 9:13 ` [PATCH v3 1/2] btrfs: replace INT_LIMIT(loff_t) with OFFSET_MAX Zhen Lei
2022-11-25 9:13 ` [PATCH v3 2/2] fs: clear a UBSAN shift-out-of-bounds warning Zhen Lei
2022-11-25 21:00 ` Al Viro [this message]
2022-11-26 1:59 ` [PATCH v3 0/2] " Leizhen (ThunderTown)
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