From: Matthew Wilcox <willy@infradead.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: Chen Huang <chenhuang5@huawei.com>,
Mark Rutland <mark.rutland@arm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Stephen Rothwell <sfr@canb.auug.org.au>,
Al Viro <viro@zeniv.linux.org.uk>,
Randy Dunlap <rdunlap@infradead.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
linux-mm <linux-mm@kvack.org>,
open list <linux-kernel@vger.kernel.org>
Subject: Re: [BUG] arm64: an infinite loop in generic_perform_write()
Date: Thu, 24 Jun 2021 12:15:46 +0100 [thread overview]
Message-ID: <YNRpYli/5/GWvaTT@casper.infradead.org> (raw)
In-Reply-To: <YNQuZ8ykN7aR+1MP@infradead.org>
On Thu, Jun 24, 2021 at 08:04:07AM +0100, Christoph Hellwig wrote:
> On Thu, Jun 24, 2021 at 04:24:46AM +0100, Matthew Wilcox wrote:
> > On Thu, Jun 24, 2021 at 11:10:41AM +0800, Chen Huang wrote:
> > > In userspace, I perform such operation:
> > >
> > > fd = open("/tmp/test", O_RDWR | O_SYNC);
> > > access_address = (char *)mmap(NULL, uio_size, PROT_READ, MAP_SHARED, uio_fd, 0);
> > > ret = write(fd, access_address + 2, sizeof(long));
> >
> > ... you know that accessing this at unaligned offsets isn't going to
> > work. It's completely meaningless. Why are you trying to do it?
>
> We still should not cause an infinite loop in kernel space due to a
> a userspace programmer error.
They're running as root and they've mapped some device memory. We can't
save them from themself. Imagine if they'd done this to the NVMe BAR.
next prev parent reply other threads:[~2021-06-24 11:17 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-23 2:39 Chen Huang
2021-06-23 2:50 ` Al Viro
2021-06-23 3:24 ` Xiaoming Ni
2021-06-23 4:27 ` Al Viro
2021-06-23 9:32 ` Catalin Marinas
2021-06-23 11:51 ` Matthew Wilcox
2021-06-23 13:04 ` Al Viro
2021-06-23 13:22 ` Mark Rutland
2021-06-24 3:10 ` Chen Huang
2021-06-24 3:24 ` Matthew Wilcox
2021-06-24 3:52 ` Chen Huang
2021-06-24 7:04 ` Christoph Hellwig
2021-06-24 11:15 ` Matthew Wilcox [this message]
2021-06-24 13:22 ` Robin Murphy
2021-06-24 16:27 ` Al Viro
2021-06-24 16:38 ` Robin Murphy
2021-06-24 16:39 ` Al Viro
2021-06-24 17:24 ` Robin Murphy
2021-06-24 18:55 ` Catalin Marinas
2021-06-24 20:36 ` Robin Murphy
2021-06-25 10:39 ` Catalin Marinas
2021-06-28 16:22 ` Robin Murphy
2021-06-29 8:30 ` Catalin Marinas
2021-06-29 10:01 ` Robin Murphy
2021-07-06 17:50 ` Catalin Marinas
2021-07-06 19:15 ` Robin Murphy
2021-07-07 9:55 ` David Laight
2021-07-07 11:04 ` Robin Murphy
2021-07-07 12:50 ` Catalin Marinas
2021-06-24 15:09 ` Catalin Marinas
2021-06-24 16:17 ` Al Viro
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