Re: [edk2-devel] [PATCH v1] ShellPkg: Fix 'ping' command Ip4 receive flow.

["Maciej Rabeda" <maciej.rabeda@linux.intel.com>]

Liming,

I assume that CVE-2019-14559 relates to problems with network drivers 
within NetworkPkg.
BZ 2032 and this patch fix address incorrect usage of IP4 protocol by 
ShellPkg 'ping' command (signalling packet recycling after triggering 
Ip4->Receive() on the same Rx token).

This issue was reported in July 2019 and occurs by executing a specific 
fuzzing scenario (as described in BZ).
As Laszlo has mentioned, it is not a new bug (introduced in 2011).

Based on the above, I can advise moving this issue out of CVE scope (and 
from stable-202002).
However, if the CVE should be treated as "overall problems with UEFI FW 
networking", then 'ping' command seems to be in CVE scope, despite the 
code residing in ShellPkg.

Thanks,
Maciej

On 28-Feb-20 12:50, Gao, Liming wrote:
> Maciej:
>    I see you submit the patch. So, you are in the loop. I don't invite you again. 😊
>    
>    Yes. I also want to get your opinion for this change. Do you think whether this fix is in CVE scope? If no, this change will be merged after this stable tag 202002. Is it OK to you?
>
> Thanks
> Liming
>> -----Original Message-----
>> From: Rabeda, Maciej <maciej.rabeda@linux.intel.com>
>> Sent: Friday, February 28, 2020 7:42 PM
>> To: devel@edk2.groups.io; Gao, Liming <liming.gao@intel.com>; Laszlo Ersek <lersek@redhat.com>; Kinney, Michael D
>> <michael.d.kinney@intel.com>; Andrew Fish <afish@apple.com>; Leif Lindholm (Linaro address) <leif.lindholm@linaro.org>
>> Cc: Ni, Ray <ray.ni@intel.com>; Gao, Zhichao <zhichao.gao@intel.com>; Armour, Nicholas <nicholas.armour@intel.com>; Fu, Siyuan
>> <siyuan.fu@intel.com>; Wu, Jiaxin <jiaxin.wu@intel.com>
>> Subject: Re: [edk2-devel] [PATCH v1] ShellPkg: Fix 'ping' command Ip4 receive flow.
>>
>> Laszlo,
>>
>> Thanks for the detailed response on the patch. Always happy to learn
>> about stuff from the past.
>>
>> Liming,
>>
>> I am currently the maintainer of NetworkPkg :) If you require additional
>> feedback from Siyuan or/and Jiaxin, that's ok.
>> Please let me know if any corrections to the patch (like CVE note) are
>> required from your point of view.
>>
>> Thanks,
>> Maciej
>>
>> On 28-Feb-20 03:59, Liming Gao wrote:
>>> Also include NetworkPkg reviewer to collect the feedback for this change.
>>>
>>> Thanks
>>> Liming
>>>> -----Original Message-----
>>>> From: Laszlo Ersek <lersek@redhat.com>
>>>> Sent: Friday, February 28, 2020 1:40 AM
>>>> To: devel@edk2.groups.io; maciej.rabeda@linux.intel.com; Gao, Liming <liming.gao@intel.com>; Kinney, Michael D
>>>> <michael.d.kinney@intel.com>; Andrew Fish <afish@apple.com>; Leif Lindholm (Linaro address) <leif.lindholm@linaro.org>
>>>> Cc: Ni, Ray <ray.ni@intel.com>; Gao, Zhichao <zhichao.gao@intel.com>; Armour, Nicholas <nicholas.armour@intel.com>
>>>> Subject: Re: [edk2-devel] [PATCH v1] ShellPkg: Fix 'ping' command Ip4 receive flow.
>>>>
>>>> On 02/27/20 14:14, Laszlo Ersek wrote:
>>>>> (+Liming and stewards; CC Nick)
>>>>>
>>>>> On 02/27/20 12:02, Maciej Rabeda wrote:
>>>>>> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2032
>>>>>>
>>>>>> 'ping' command's receive flow utilizes a single Rx token which it
>>>>>> attempts to reuse before recycling the previously received packet.
>>>>>> This causes a situation where under ICMP traffic,
>>>>>> Ping6OnEchoReplyReceived() function will receive an already
>>>>>> recycled packet with EFI_SUCCESS token status and finally
>>>>>> dereference invalid pointers from RxData structure.
>>>>>>
>>>>>> Cc: Ray Ni <ray.ni@intel.com>
>>>>>> Cc: Zhichao Gao <zhichao.gao@intel.com>
>>>>>> Signed-off-by: Maciej Rabeda <maciej.rabeda@linux.intel.com>
>>>>>> ---
>>>>>>    ShellPkg/Library/UefiShellNetwork1CommandsLib/Ping.c | 9 +++++----
>>>>>>    1 file changed, 5 insertions(+), 4 deletions(-)
>>>>>>
>>>>>> diff --git a/ShellPkg/Library/UefiShellNetwork1CommandsLib/Ping.c b/ShellPkg/Library/UefiShellNetwork1CommandsLib/Ping.c
>>>>>> index 23567fa2c1bb..a3fa32515192 100644
>>>>>> --- a/ShellPkg/Library/UefiShellNetwork1CommandsLib/Ping.c
>>>>>> +++ b/ShellPkg/Library/UefiShellNetwork1CommandsLib/Ping.c
>>>>>> @@ -614,6 +614,11 @@ Ping6OnEchoReplyReceived (
>>>>>>
>>>>>>    ON_EXIT:
>>>>>>
>>>>>> +  //
>>>>>> +  // Recycle the packet before reusing RxToken
>>>>>> +  //
>>>>>> +  gBS->SignalEvent (Private->IpChoice == PING_IP_CHOICE_IP6?((EFI_IP6_RECEIVE_DATA*)Private->RxToken.Packet.RxData)-
>>>>> RecycleSignal:((EFI_IP4_RECEIVE_DATA*)Private->RxToken.Packet.RxData)->RecycleSignal);
>>>>>> +
>>>>>>      if (Private->RxCount < Private->SendNum) {
>>>>>>        //
>>>>>>        // Continue to receive icmp echo reply packets.
>>>>>> @@ -632,10 +637,6 @@ ON_EXIT:
>>>>>>        //
>>>>>>        Private->Status = EFI_SUCCESS;
>>>>>>      }
>>>>>> -  //
>>>>>> -  // Singal to recycle the each rxdata here, not at the end of process.
>>>>>> -  //
>>>>>> -  gBS->SignalEvent (Private->IpChoice == PING_IP_CHOICE_IP6?((EFI_IP6_RECEIVE_DATA*)Private->RxToken.Packet.RxData)-
>>>>> RecycleSignal:((EFI_IP4_RECEIVE_DATA*)Private->RxToken.Packet.RxData)->RecycleSignal);
>>>>>>    }
>>>>>>
>>>>>>    /**
>>>>>>
>>>>> (1) This patch proposes to fix one of the BZs (2032) that fall under
>>>>> CVE-2019-14559 (joint tracker: 2550).
>>>>>
>>>>> Consequently:
>>>>>
>>>>> (1a) Do we want to include this in the upcoming stable tag?
>>>>>
>>>>> If so, we might want to extend the hard feature freeze by a few days.
>>>>>
>>>>> (1b) Please append the string " (CVE-2019-14559)" -- note the separating
>>>>> space! -- to the subject line.
>>>>>
>>>>> (2) However: I remember from an earlier Bugzilla entry (can't tell
>>>>> off-hand, which one, sorry) that ShellPkg issues are *never* considered
>>>>> CVE-worthy, because the shell is not considered a "production element"
>>>>> of the UEFI boot path.
>>>> I misremembered -- there is indeed a comment like that, in the TianoCore
>>>> bugzilla, but it does not refer to ShellPkg. It refers to StdLib (which
>>>> has since been split off to the edk2-libc project):
>>>>
>>>> https://bugzilla.tianocore.org/show_bug.cgi?id=1510#c1
>>>>
>>>>       StdLib is supposed to be used only by applications in shell, all of
>>>>       which are meant for debug, diagnosis and/or test purpose, not for
>>>>       product UEFI BIOS. Any issue in it will not be taken as security
>>>>       issue but just normal bug.
>>>>
>>>> Sorry about causing confusion. So, the ShellPkg maintainers should
>>>> decide what to do about this bug (keep it under the CVE scope vs.
>>>> exclude it from the CVE scope; and then, propose it for the stable tag
>>>> or merge it afterwards).
>>>>
>>>> One data point: the bug appears to go back to the inception of the Ping
>>>> command, in historical commit 68fb05272b45 ("Add Network1 profile.",
>>>> 2011-03-25). It's not a new bug, it seems.
>>>>
>>>> Thanks
>>>> Laszlo
>>>>
>>>>> TianoCore#2032 was originally filed for NetworkPkg, and indeed that
>>>>> seemed to justify the CVE assignment. However, now that Nick's and
>>>>> Maciej's analysis shows that NetworkPkg is unaffected (and we know, per
>>>>> above, that ShellPkg is not CVE-worthy), should we rather *remove* this
>>>>> BZ from the CVE-2019-14559 umbrella?
>>>>>
>>>>> Because, in that case, modifying the subject line on the patch is not
>>>>> necessary; and more importantly, we might not even want to put this into
>>>>> edk2-stable202002. (It's still a bugfix, but may not be important enough.)
>>>>>
>>>>> Thanks!
>>>>> Laszlo
>>>>>
>>> 
>>>