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Re: [Qemu-ppc] [Qemu-devel] [PATCH 1/1] block/nbd: fix segmentation faul

From: Murilo Opsfelder Araújo
Subject: Re: [Qemu-ppc] [Qemu-devel] [PATCH 1/1] block/nbd: fix segmentation fault when .desc is not null-terminated
Date: Fri, 5 Jan 2018 12:47:10 -0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0

On 01/05/2018 11:57 AM, Eric Blake wrote:
> On 01/05/2018 07:32 AM, Murilo Opsfelder Araujo wrote:
>> The find_desc_by_name() from util/qemu-option.c relies on the .name not being
>> NULL to call strcmp(). This check becomes unsafe when the list is not
>> NULL-terminated, which is the case of nbd_runtime_opts in block/nbd.c, and 
>> can
>> result in segmentation fault when strcmp() tries to access an invalid memory:
> Thanks for the report and patch.  Adding qemu-stable in cc.
>> This patch fixes the segmentation fault in strcmp() by adding a NULL element 
>> at
>> the end of nbd_runtime_opts.desc list, which is the common practice to most 
>> of
>> other structs like runtime_opts in block/null.c. Thus, the desc[i].name != 
>> check becomes safe because it will not evaluate to true when .desc list 
>> reached
>> its end.
>> Reported-by: R. Nageswara Sastry <address@hidden>
>> Buglink: https://bugs.launchpad.net/qemu/+bug/1727259
>> Signed-off-by: Murilo Opsfelder Araujo <address@hidden>
> I'll update the commit message to add in the commit id that introduced
> the problem, as well as check that other QemuOptsList do not have a
> similar problem; I'm queueing this on the NBD tree and will submit a
> pull request soon.
> Reviewed-by: Eric Blake <address@hidden>

Hi, Eric.

A quick look brought my attention to:

530:static QemuOptsList ssh_runtime_opts = {

I've sent a patch to fix it too.


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