Re: [Qemu-devel] [PATCH] qga: Fix possible freed memory accessing

[Eric Blake <eblake@redhat.com>]

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On 09/18/2014 06:42 AM, zhanghailiang wrote:
> On 2014/9/18 20:17, Eric Blake wrote:
>> On 09/17/2014 09:33 PM, zhanghailiang wrote:
>>> If readdir_r fails, error_setg_errno will reference the freed
>>> pointer *dirpath*.
>>>
>>> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
>>> ---
>>>   qga/commands-posix.c | 10 ++++++----
>>>   1 file changed, 6 insertions(+), 4 deletions(-)
>>
>>>       for (;;) {
>>>           if (readdir_r(dir, &entry, &result) != 0) {
>>
>> Eww.  We're using readdir_r?  That's an inherently broken interface,
>> which can risk buffer overflow.  readdir should be preferred.
>>
>> http://austingroupbugs.net/view.php?id=696
>>
> 
> Yes, it is! Should i fix it in this patch together?;)

Switching to readdir would be welcome, and would probably be enough of a
rewrite that it would also fix the use-after-free without trying to
break it into two patches.  You're welcome to try that as a v2.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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