Re: Pressing ESC from "PXE windows Boot manager" causes ASSERT

[Andrew Fish <afish@apple.com>]

Karunakar,

Every Pool allocation has a header and a tail data structure that is outside of the user visible data. Both these structures have signatures. The ASSERT you are seeing is a bad signature in the header so that looks like a buffer underflow. It could also be a use after free bug.

Head:
POOL_HEAD
Buffer:
User Data
Tail:
POOL_TAIL

Given the checks only happen on Free it is possible it could be a buffer overflow on a buffer that has not yet been freed that runs into this buffer. 

If you have a debugger dumping the memory before and after the buffer can some times be useful. The pattern might give you some clues. 

Thanks,

Andrew Fish

> On May 23, 2017, at 10:16 PM, Karunakar P <karunakarp@amiindia.co.in> wrote:
> 
> Hello All,
> 
> The ASSERT happens in the following function
> 
> /**
>  Internal function to free a pool entry.
>  Caller must have the memory lock held
> 
>  @param  Buffer                 The allocated pool entry to free
>  @param  PoolType               Pointer to pool type
> 
>  @retval EFI_INVALID_PARAMETER  Buffer not valid
>  @retval EFI_SUCCESS            Buffer successfully freed.
> 
> **/
> EFI_STATUS
> CoreFreePoolI (
>  IN VOID               *Buffer,
>  OUT EFI_MEMORY_TYPE   *PoolType OPTIONAL
>  )
> {
> .
> .
> ASSERT(Buffer != NULL);
>  //
>  // Get the head & tail of the pool entry
>  //
>  Head = CR (Buffer, POOL_HEAD, Data, POOL_HEAD_SIGNATURE);	// ASSERT happens here
>  ASSERT(Head != NULL);
> .
> .
> }
> 
> We are using NetworkPkg: SHA- ef810bc807188224a752ffbcf5e7f4b651291cee
> 
> I think  here I'm unable attach the files.
> You can find the attached screenshots in the following Bug571
> https://bugzilla.tianocore.org/show_bug.cgi?id=571
> 
> Thanks,
> Karunakar
> 
> 
> -----Original Message-----
> From: Ye, Ting [mailto:ting.ye@intel.com] 
> Sent: Wednesday, May 24, 2017 10:29 AM
> To: Karunakar P; edk2-devel@lists.01.org
> Subject: RE: Pressing ESC from "PXE windows Boot manager" causes ASSERT
> 
> Hi Karunakar,
> 
> Sorry I did not find your attached files. Would you please send them again? Besides that, do you mind telling us which code base are you using for PXE boot?  Are you using some revision of EDKII main trunk or UDK release?
> 
> Thanks,
> Ting
> 
> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Karunakar P
> Sent: Wednesday, May 24, 2017 12:20 PM
> To: edk2-devel@lists.01.org
> Subject: [edk2] Pressing ESC from "PXE windows Boot manager" causes ASSERT
> 
> Hi All,
> 
> We have facing an issue with PXE boot.
> [Issue]
> When ESC is pressed from Windows Boot manager during PXE boot (IPv4 or IPv6) system Hangs with following ASSERT
> 
> ASSERT [DxeCore] \MdeModulePkg\Core\Dxe\Mem\Pool.c : CR has Bad Signature
> 
> [Reproduction Steps]
> 1. Perform UEFI PXEv4 or UEFI PXEv6 boot 2. It will start PXE boot over IPv4/6 and Downloads NBP file successfully.
>   Attached the Screenshot for the same(ScreenShot1.jpg)
> 
>   It will Displays the info like "Press ENTER for network boot service"
>   Attached Screensho(ScreenShot2.jpg)
> 
> 3. Press ENTER and then press ESC immediately to see the Windows Boot Manager Menu
>   It will list the available Operating Systems
>   Attached the screenshot(ScreenShot3.png)
> 
> 4. Press ESC to come back to Setup or next Boot option
> 
> [Result]
> System hangs with ASSERT
> 
> [Expected Result]
> On pressing ESC from Windows Boot Manager, it should come back to setup/Next boot option in boot order
> 
> Note:
> We have PXE server configured in Windows Server 2012 R2.
> 
> Please look into it.
> 
> 
> Thanks,
> karunakar
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