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From: Matthew Wilcox <willy@infradead.org>
To: Zhen Lei <thunder.leizhen@huawei.com>
Cc: Christoph Hellwig <hch@infradead.org>,
	"Darrick J . Wong" <djwong@kernel.org>,
	linux-xfs <linux-xfs@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH -next 1/1] iomap: Fix a false positive of UBSAN in iomap_seek_data()
Date: Fri, 2 Jul 2021 20:56:21 +0100	[thread overview]
Message-ID: <YN9vZfo+84gizjtf@casper.infradead.org> (raw)
In-Reply-To: <20210702092109.2601-1-thunder.leizhen@huawei.com>

On Fri, Jul 02, 2021 at 05:21:09PM +0800, Zhen Lei wrote:
> Move the evaluation expression "size - offset" after the "if (offset < 0)"
> judgment statement to eliminate a false positive produced by the UBSAN.
> 
> No functional changes.
> 
> ==========================================================================
> UBSAN: Undefined behaviour in fs/iomap.c:1435:9
> signed integer overflow:
> 0 - -9223372036854775808 cannot be represented in type 'long long int'

I don't understand.  I thought we defined the behaviour of signed
integer overflow in the kernel with whatever-the-gcc-flag-is?


  parent reply	other threads:[~2021-07-02 19:58 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-02  9:21 [PATCH -next 1/1] iomap: Fix a false positive of UBSAN in iomap_seek_data() Zhen Lei
2021-07-02  9:34 ` Christoph Hellwig
2021-07-02 11:50   ` Leizhen (ThunderTown)
2021-07-05  3:29     ` Leizhen (ThunderTown)
2021-07-05  3:43       ` Matthew Wilcox
2021-07-05  4:05         ` Leizhen (ThunderTown)
2021-07-04 13:51   ` Matthew Wilcox
2021-07-02 19:56 ` Matthew Wilcox [this message]
2021-07-05  3:35   ` Leizhen (ThunderTown)
2021-07-06 11:08     ` Matthew Wilcox
2021-07-06 11:59       ` Matthew Wilcox

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