From: Rich Felker <dalias@libc.org>
To: musl@lists.openwall.com
Cc: Minqiang Chen <ptpt52@gmail.com>
Subject: Re: [PATCH v1] mman: fix mmap pass wrong offset to kernel
Date: Mon, 16 Oct 2017 12:27:43 -0400 [thread overview]
Message-ID: <20171016162743.GP1627@brightrain.aerifal.cx> (raw)
In-Reply-To: <20171016110318.GQ15263@port70.net>
On Mon, Oct 16, 2017 at 01:03:18PM +0200, Szabolcs Nagy wrote:
> * Minqiang Chen <ptpt52@gmail.com> [2017-10-16 09:09:32 +0800]:
> >
> > musl: fix mmap pass wrong offset to kernel
> >
> >
> >
> > for example off_t x=0x8d9eb000, the x/4096 result is 0xfff8d9eb,
> > not 0x8d9eb as expecting
> >
>
> off_t is 64bit, not 32bit, so x/4096 should not signextend.
> you need to investigate this problem more.
I suspect the calling code stored the offset 0x8d9eb000 in a signed
32-bit variable (converting it to a negative value) and then passed
the resulting negative value to mmap.
Rich
next prev parent reply other threads:[~2017-10-16 16:27 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-16 1:09 Minqiang Chen
2017-10-16 11:03 ` Szabolcs Nagy
2017-10-16 16:27 ` Rich Felker [this message]
[not found] ` <94E25077-4463-454D-96BF-BA1DA9166F60@gmail.com>
2017-10-21 4:20 ` Rich Felker
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