[ros-dev] [ros-diffs] [gedmurphy] 70408: [NTOSKRNL] - Raise the IRQL when enumerating device lists so it doesn't get edited mid-listing - Don't hardcode the pointer size when checking the buffer size

[Ged Murphy]

It depends on whether we want to emulate the 2k3 kernel or not.

I noticed in my 2k3 fltmgr testing that IoEnumerateDeviceObjectList runs at
DPC for the entirety of the function. This was changed in the NT6 kernel to
use a lock, which is indeed the LockQueueIoDatabaseLock Hermes mentioned.

I'm happy to use the spinlock (and would prefer to myself), but any move
towards NT6 normally results in an angry email, so I opted for the 2k3
approach  ;)

Ged.


-----Original Message-----
From: Ros-dev [mailto:ros-dev-bounces at reactos.org] On Behalf Of Hermès
BÉLUSCA - MAÏTO
Sent: 29 December 2015 16:08
To: 'ReactOS Development List' <ros-dev at reactos.org>
Subject: Re: [ros-dev] [ros-diffs] [gedmurphy] 70408: [NTOSKRNL] - Raise the
IRQL when enumerating device lists so it doesn't get edited mid-listing -
Don't hardcode the pointer size when checking the buffer size

Yes this should be a spinlock involved instead, for example the
"LockQueueIoDatabaseLock" (queued) spinlock that we already use in other
places in the code.

-----Message d'origine-----
De : Ros-dev [mailto:ros-dev-bounces at reactos.org] De la part de Thomas Faber
Envoyé : mardi 29 décembre 2015 13:20 À : ros-dev at reactos.org Objet : Re:
[ros-dev] [ros-diffs] [gedmurphy] 70408: [NTOSKRNL] - Raise the IRQL when
enumerating device lists so it doesn't get edited mid-listing - Don't
hardcode the pointer size when checking the buffer size

Uhm... raising the IRQL is not a synchronization mechanism. Should there be
a spinlock involved?


On 2015-12-23 12:26, gedmurphy at svn.reactos.org wrote:
> Author: gedmurphy
> Date: Wed Dec 23 11:26:28 2015
> New Revision: 70408
> 
> URL: http://svn.reactos.org/svn/reactos?rev=70408&view=rev
> Log:
> [NTOSKRNL]
> - Raise the IRQL when enumerating device lists so it doesn't get 
> edited mid-listing
> - Don't hardcode the pointer size when checking the buffer size
> 
> Modified:
>     trunk/reactos/ntoskrnl/io/iomgr/device.c
> 
> Modified: trunk/reactos/ntoskrnl/io/iomgr/device.c
> URL: 
> http://svn.reactos.org/svn/reactos/trunk/reactos/ntoskrnl/io/iomgr/dev
> ice.c?rev=70408&r1=70407&r2=70408&view=diff
>
============================================================================
==
> --- trunk/reactos/ntoskrnl/io/iomgr/device.c	[iso-8859-1] (original)
> +++ trunk/reactos/ntoskrnl/io/iomgr/device.c	[iso-8859-1] Wed Dec 23
11:26:28 2015
> @@ -1088,6 +1088,10 @@
>  {
>      ULONG ActualDevices = 1;
>      PDEVICE_OBJECT CurrentDevice = DriverObject->DeviceObject;
> +    KIRQL OldIrql;
> +
> +    /* Raise to dispatch level */
> +    KeRaiseIrql(DISPATCH_LEVEL, &OldIrql);
>  
>      /* Find out how many devices we'll enumerate */
>      while ((CurrentDevice = CurrentDevice->NextDevice))
> ActualDevices++; @@ -1099,13 +1103,14 @@
>      *ActualNumberDeviceObjects = ActualDevices;
>  
>      /* Check if we can support so many */
> -    if ((ActualDevices * 4) > DeviceObjectListSize)
> +    if ((ActualDevices * sizeof(PDEVICE_OBJECT)) >
> + DeviceObjectListSize)
>      {
>          /* Fail because the buffer was too small */
> +        KeLowerIrql(OldIrql);
>          return STATUS_BUFFER_TOO_SMALL;
>      }
>  
> -    /* Check if the caller only wanted the size */
> +    /* Check if the caller wanted the device list */
>      if (DeviceObjectList)
>      {
>          /* Loop through all the devices */ @@ -1123,6 +1128,9 @@
>              DeviceObjectList++;
>          }
>      }
> +
> +    /* Return back to previous IRQL */
> +    KeLowerIrql(OldIrql);
>  
>      /* Return the status */
>      return STATUS_SUCCESS;
> 
> 


_______________________________________________
Ros-dev mailing list
Ros-dev at reactos.org
http://www.reactos.org/mailman/listinfo/ros-dev

_______________________________________________
Ros-dev mailing list
Ros-dev at reactos.org
http://www.reactos.org/mailman/listinfo/ros-dev