linux-kernel - Re: [PATCH] scsi: virtio-scsi: Fix address translation failure of HighMem pages used by sg list

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAKviJvVrrtyjFOzu7jmmD7cpXZcXtyQ+7HDy1G1o2_a0JRss5w@mail.gmail.com>
Date:	Wed, 25 Jul 2012 19:44:28 +0800
From:	Sen Wang <kelvin.xupt@...il.com>
To:	Paolo Bonzini <pbonzini@...hat.com>
Cc:	Wang Sen <senwang@...ux.vnet.ibm.com>, linux-scsi@...r.kernel.org,
	JBottomley@...allels.com, stefanha@...ux.vnet.ibm.com,
	mc@...ux.vnet.ibm.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] scsi: virtio-scsi: Fix address translation failure of
 HighMem pages used by sg list

2012/7/25 Paolo Bonzini <pbonzini@...hat.com>:
> Il 25/07/2012 10:29, Wang Sen ha scritto:
>> When using the commands below to write some data to a virtio-scsi LUN of the
>> QEMU guest(32-bit) with 1G physical memory(qemu -m 1024), the qemu will crash.
>>
>>       # sudo mkfs.ext4 /dev/sdb  (/dev/sdb is the virtio-scsi LUN.)
>>       # sudo mount /dev/sdb /mnt
>>       # dd if=/dev/zero of=/mnt/file bs=1M count=1024
>>
>> In current implementation, sg_set_buf is called to add buffers to sg list which
>> is put into the virtqueue eventually. But there are some HighMem pages in
>> table->sgl can not get virtual address by sg_virt. So, sg_virt(sg_elem) may
>> return NULL value. This will cause QEMU exit when virtqueue_map_sg is called
>> in QEMU because an invalid GPA is passed by virtqueue.
>
> Heh, I was compiling (almost) the same patch as we speak. :)

Uh, what a coincidence! :)

>
> I've never seen QEMU crash; the VM would more likely just fail to boot
> with a panic.  But it's the same bug anyway.

I never met this before. How this situation happens?

>
>> My solution is using sg_set_page instead of sg_set_buf.
>>
>> I have tested the patch on my workstation. QEMU would not crash any more.
>>
>> Signed-off-by: Wang Sen <senwang@...ux.vnet.ibm.com>
>> ---
>>  drivers/scsi/virtio_scsi.c |    3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
>> index 1b38431..fc5c88a 100644
>> --- a/drivers/scsi/virtio_scsi.c
>> +++ b/drivers/scsi/virtio_scsi.c
>> @@ -198,7 +198,8 @@ static void virtscsi_map_sgl(struct scatterlist *sg, unsigned int *p_idx,
>>       int i;
>>
>>       for_each_sg(table->sgl, sg_elem, table->nents, i)
>> -             sg_set_buf(&sg[idx++], sg_virt(sg_elem), sg_elem->length);
>> +             sg_set_page(&sg[idx++], sg_page(sg_elem), sg_elem->length,
>> +                     sg_elem->offset);
>
> This can simply be
>
>    sg[idx++] = *sg_elem;
>

Yes, I saw your another E-mail. I think you're right. Simply calling
sg_set_page can not handle
the flag bits correctly. So, I'll repost the patch soon. Thank you!

> Can you repost it with this change, and also add stable@...r.kernel.org
> to the Cc?  Thanks very much!
>
> Paolo
> --
> To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
> the body of a message to majordomo@...r.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html



-- 
------------------------------------------
Wang Sen
Addr: XUPT,Xi'an,Shaanxi,China
Email: kelvin.xupt@...il.com
------------------------------------------
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/