RtlEqualUnicodeString is in a pagable code section in ntoskrnl, RtlCompareMemory is not. Holding a spinlock means we're at DISPATCH_LEVEL and can't access pagable code/data.
On 2014-10-16 19:32, Hermès BÉLUSCA - MAÏTO wrote: > What is the *root* reason for this problem (ok I’ve seen in the comment, > “paged code” and “holding spin lock”, but it doesn’t answer my question)? > Because I’ve looked at our code of RtlEqualUnicodeString and I see that it > just calls RtlCompareUnicodeString that in turns just loops over the two > memory buffers, checks their contents (and in case we check for char case, > calls RtlUpcaseUnicodeChar). And RtlCompareMemory does that, too? What I’m > missing? > > Hermès. > > > ------------------------------------------------------------------------- > Author: tfaber > Date: Thu Oct 16 16:40:13 2014 > New Revision: 64762 > > URL: http://svn.reactos.org/svn/reactos?rev=64762&view=rev > Log: > [NPFS] > - Don't call RtlEqualUnicodeString (paged code) while holding a spin lock. > Powered by Driver Verifier. > > Modified: > trunk/reactos/drivers/filesystems/npfs/waitsup.c > > Modified: trunk/reactos/drivers/filesystems/npfs/waitsup.c > URL: > http://svn.reactos.org/svn/reactos/trunk/reactos/drivers/filesystems/npfs/wa > itsup.c?rev=64762&r1=64761&r2=64762&view=diff > ============================================================================ > == > --- trunk/reactos/drivers/filesystems/npfs/waitsup.c [iso-8859-1] > (original) > +++ trunk/reactos/drivers/filesystems/npfs/waitsup.c [iso-8859-1] Thu Oct > 16 16:40:13 2014 > @@ -97,6 +97,22 @@ > { > InitializeListHead(&WaitQueue->WaitList); > KeInitializeSpinLock(&WaitQueue->WaitLock); > +} > + > +static > +BOOLEAN > +NpEqualUnicodeString(IN PCUNICODE_STRING String1, > + IN PCUNICODE_STRING String2) > +{ > + SIZE_T EqualLength; > + > + if (String1->Length != String2->Length) > + return FALSE; > + > + EqualLength = RtlCompareMemory(String1->Buffer, > + String2->Buffer, > + String1->Length); > + return EqualLength == String1->Length; > } > > NTSTATUS > @@ -156,7 +172,8 @@ > PipeName.MaximumLength = PipeName.Length; > } > > - if (RtlEqualUnicodeString(&WaitName, &PipeName, FALSE)) > + /* Can't use RtlEqualUnicodeString with a spinlock held */ > + if (NpEqualUnicodeString(&WaitName, &PipeName)) > { > /* Found a matching wait. Cancel it */ > RemoveEntryList(&WaitIrp->Tail.Overlay.ListEntry); > _______________________________________________ Ros-dev mailing list Ros-dev@reactos.org http://www.reactos.org/mailman/listinfo/ros-dev
