From mboxrd@z Thu Jan  1 00:00:00 1970
From: Sasha Levin <sasha.levin@oracle.com>
Subject: Re: Network hangs when communicating with host
Date: Tue, 20 Oct 2015 09:58:51 -0400
Message-ID: <5626489B.1020309@oracle.com>
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Cc: syzkaller@googlegroups.com, Sasha Levin <levinsasha928@gmail.com>,
	Pekka Enberg <penberg@kernel.org>,
	Asias He <asias.hejun@gmail.com>, penberg@cs.helsinki.fi,
	Cyrill Gorcunov <gorcunov@gmail.com>,
	Will Deacon <will.deacon@arm.com>, matt@ozlabs.org,
	Michael Ellerman <michael@ellerman.id.au>,
	Prasad Joshi <prasadjoshi124@gmail.com>, marc.zyngier@arm.com,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	mingo@elte.hu, gorcunov@openvz.org, kvm@vger.kernel.org,
	Kostya Serebryany <kcc@google.com>,
	Evgenii Stepanov <eugenis@google.com>,
	Alexey Samsonov <samsonov@google.com>,
	Alexander Potapenko <glider@google.com>
To: Dmitry Vyukov <dvyukov@google.com>
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On 10/20/2015 09:42 AM, Dmitry Vyukov wrote:
> I now have another issue. My binary fails to mmap a file within lkvm
> sandbox. The same binary works fine on host and in qemu. I've added
> strace into sandbox script, and here is the output:
> 
> [pid   837] openat(AT_FDCWD, "syzkaller-shm048878722", O_RDWR|O_CLOEXEC) = 5
> [pid   837] mmap(NULL, 1048576, PROT_READ|PROT_WRITE, MAP_SHARED, 5,
> 0) = -1 EINVAL (Invalid argument)
> 
> I don't see anything that can potentially cause EINVAL here. Is it
> possible that lkvm somehow affects kernel behavior here?
> 
> I run lkvm as:
> 
> $ taskset 1 /kvmtool/lkvm sandbox --disk syz-0 --mem=2048 --cpus=2
> --kernel /arch/x86/boot/bzImage --network mode=user --sandbox
> /workdir/kvm/syz-0.sh

It's possible that something in the virtio-9p layer is broken. I'll give
it a look in the evening.


Thanks,
Sasha