* Re: [PATCH] MdeModulePkg/SmmCore: Fix hang due to already-freed memory deference
2018-02-01 16:12 ` [PATCH] MdeModulePkg/SmmCore: Fix hang due to already-freed memory deference Laszlo Ersek
@ 2018-02-02 0:54 ` Ni, Ruiyu
2018-02-02 5:40 ` Shi, Steven
1 sibling, 0 replies; 4+ messages in thread
From: Ni, Ruiyu @ 2018-02-02 0:54 UTC (permalink / raw)
To: Laszlo Ersek, Shi, Steven
Cc: Yao, Jiewen, Zeng, Star, edk2-devel@lists.01.org
> -----Original Message-----
> From: Laszlo Ersek [mailto:lersek@redhat.com]
> Sent: Friday, February 2, 2018 12:12 AM
> To: Ni, Ruiyu <ruiyu.ni@intel.com>; edk2-devel@lists.01.org
> Cc: Yao, Jiewen <jiewen.yao@intel.com>; Zeng, Star <star.zeng@intel.com>
> Subject: Re: [edk2] [PATCH] MdeModulePkg/SmmCore: Fix hang due to already-
> freed memory deference
>
> Hello Ray,
>
> On 02/01/18 11:15, Ruiyu Ni wrote:
> > SmiHandlerUnRegister() validates the DispatchHandle by checking
> > whether the first 32bit matches to a certain signature
> > (SMI_HANDLER_SIGNATURE).
> > But if a caller calls *UnRegister() twice and the memory freed by
> > first call still contains the signature, the second hang may hang.
> >
> > The patch fixes this issue by locating the DispatchHandle in all SMI
> > handlers, instead of checking the signature.
> >
> > Contributed-under: TianoCore Contribution Agreement 1.1
> > Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
> > Cc: Jiewen Yao <jiewen.yao@intel.com>
> > Cc: Star Zeng <star.zeng@intel.com>
> > ---
> > MdeModulePkg/Core/PiSmmCore/Smi.c | 37
> > ++++++++++++++++++++++++++++++++-----
> > 1 file changed, 32 insertions(+), 5 deletions(-)
>
> I'm mildly curious: can we just zero out the signature when the de-registration /
> freeing happens? Otherwise, the nested loop added below will penalize
> (performance-wise) correctly written client code as well.
>
> > diff --git a/MdeModulePkg/Core/PiSmmCore/Smi.c
> > b/MdeModulePkg/Core/PiSmmCore/Smi.c
> > index ad483a1877ce..6596ea9560d1 100644
> > --- a/MdeModulePkg/Core/PiSmmCore/Smi.c
> > +++ b/MdeModulePkg/Core/PiSmmCore/Smi.c
> > @@ -290,6 +290,7 @@ SmiHandlerUnRegister (
> > SmiEntry = SmiHandler->SmiEntry;
> >
> > RemoveEntryList (&SmiHandler->Link);
> > + SmiHandler->Signature = 0;
> > FreePool (SmiHandler);
> >
> > if (SmiEntry == NULL) {
>
> Generally, if client code violates an interface contract, then the called function is
> not responsible for catching the error and preventing undefined behavior. For
> "quality of service", we can go to certain lengths nonetheless, but it should
> hopefully not hurt valid client code.
>
> For example, I seem to remember that the list data structure implementation
> checks the internal consistency (which can be costly) only if a PCD is set to a
> certain value. Is that right? Is it an option here? (If the above zeroing is not good
> for some reason.)
>
> Anyway, I'm asking mainly for my own education.
>
> Thanks!
> Laszlo
Laszlo,
I agree your fix is quite simple and no performance impact.
But if caller supplies an invalid DispatchHandle, checking the signature
means to read the memory whose address is provided by caller.
I remember Steven Shi submitted several bugs regarding this because
he considered such reading access is bad.
Steven,
Any comments?
>
> > diff --git a/MdeModulePkg/Core/PiSmmCore/Smi.c
> > b/MdeModulePkg/Core/PiSmmCore/Smi.c
> > index ad483a1877..0c09e7fa10 100644
> > --- a/MdeModulePkg/Core/PiSmmCore/Smi.c
> > +++ b/MdeModulePkg/Core/PiSmmCore/Smi.c
> > @@ -1,7 +1,7 @@
> > /** @file
> > SMI management.
> >
> > - Copyright (c) 2009 - 2017, Intel Corporation. All rights
> > reserved.<BR>
> > + Copyright (c) 2009 - 2018, Intel Corporation. All rights
> > + reserved.<BR>
> > This program and the accompanying materials are licensed and made
> available
> > under the terms and conditions of the BSD License which accompanies this
> > distribution. The full text of the license may be found at
> > @@ -276,14 +276,41 @@ SmiHandlerUnRegister ( {
> > SMI_HANDLER *SmiHandler;
> > SMI_ENTRY *SmiEntry;
> > + LIST_ENTRY *EntryLink;
> > + LIST_ENTRY *HandlerLink;
> >
> > - SmiHandler = (SMI_HANDLER *) DispatchHandle;
> > -
> > - if (SmiHandler == NULL) {
> > + if (DispatchHandle == NULL) {
> > return EFI_INVALID_PARAMETER;
> > }
> >
> > - if (SmiHandler->Signature != SMI_HANDLER_SIGNATURE) {
> > + //
> > + // Look for it in root SMI handlers // SmiHandler = NULL; for (
> > + HandlerLink = GetFirstNode (&mRootSmiEntry.SmiHandlers)
> > + ; !IsNull (&mRootSmiEntry.SmiHandlers, HandlerLink) && (SmiHandler !=
> DispatchHandle)
> > + ; HandlerLink = GetNextNode (&mRootSmiEntry.SmiHandlers, HandlerLink)
> > + ) {
> > + SmiHandler = CR (HandlerLink, SMI_HANDLER, Link,
> > + SMI_HANDLER_SIGNATURE); }
> > +
> > + //
> > + // Look for it in non-root SMI handlers // for ( EntryLink =
> > + GetFirstNode (&mSmiEntryList)
> > + ; !IsNull (&mSmiEntryList, EntryLink) && (SmiHandler != DispatchHandle)
> > + ; EntryLink = GetNextNode (&mSmiEntryList, EntryLink)
> > + ) {
> > + SmiEntry = CR (EntryLink, SMI_ENTRY, AllEntries, SMI_ENTRY_SIGNATURE);
> > + for ( HandlerLink = GetFirstNode (&SmiEntry->SmiHandlers)
> > + ; !IsNull (&SmiEntry->SmiHandlers, HandlerLink) && (SmiHandler !=
> DispatchHandle)
> > + ; HandlerLink = GetNextNode (&SmiEntry->SmiHandlers, HandlerLink)
> > + ) {
> > + SmiHandler = CR (HandlerLink, SMI_HANDLER, Link,
> SMI_HANDLER_SIGNATURE);
> > + }
> > + }
> > +
> > + if (SmiHandler != DispatchHandle) {
> > return EFI_INVALID_PARAMETER;
> > }
> >
> >
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] MdeModulePkg/SmmCore: Fix hang due to already-freed memory deference
2018-02-01 16:12 ` [PATCH] MdeModulePkg/SmmCore: Fix hang due to already-freed memory deference Laszlo Ersek
2018-02-02 0:54 ` Ni, Ruiyu
@ 2018-02-02 5:40 ` Shi, Steven
1 sibling, 0 replies; 4+ messages in thread
From: Shi, Steven @ 2018-02-02 5:40 UTC (permalink / raw)
To: Laszlo Ersek, Ni, Ruiyu, edk2-devel@lists.01.org; +Cc: Yao, Jiewen, Zeng, Star
Hi Laszlo,
Check the DispatchHandle valid in internal handle set before using it to reference its Signature data is majorly to avoid use-after-free problem here, it also can defense if an input handle is invalid but has a valid signature occasionally or deliberately.
> Generally, if client code violates an interface contract, then the called function is not responsible for catching the error and preventing undefined behavior.
> For "quality of service", we can go to certain lengths nonetheless, but it should hopefully not hurt valid client code.
If the called function is an interface function, I think it is necessary to validate the inputs before use them to reference other internal data. This way can make the service code more secure.
Steven Shi
Intel\SSG\STO\UEFI Firmware
Tel: +86 021-61166522
iNet: 821-6522
> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of
> Laszlo Ersek
> Sent: Friday, February 2, 2018 12:12 AM
> To: Ni, Ruiyu <ruiyu.ni@intel.com>; edk2-devel@lists.01.org
> Cc: Yao, Jiewen <jiewen.yao@intel.com>; Zeng, Star <star.zeng@intel.com>
> Subject: Re: [edk2] [PATCH] MdeModulePkg/SmmCore: Fix hang due to
> already-freed memory deference
>
> Hello Ray,
>
> On 02/01/18 11:15, Ruiyu Ni wrote:
> > SmiHandlerUnRegister() validates the DispatchHandle by checking
> > whether the first 32bit matches to a certain signature
> > (SMI_HANDLER_SIGNATURE).
> > But if a caller calls *UnRegister() twice and the memory freed by
> > first call still contains the signature, the second hang may hang.
> >
> > The patch fixes this issue by locating the DispatchHandle
> > in all SMI handlers, instead of checking the signature.
> >
> > Contributed-under: TianoCore Contribution Agreement 1.1
> > Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
> > Cc: Jiewen Yao <jiewen.yao@intel.com>
> > Cc: Star Zeng <star.zeng@intel.com>
> > ---
> > MdeModulePkg/Core/PiSmmCore/Smi.c | 37
> ++++++++++++++++++++++++++++++++-----
> > 1 file changed, 32 insertions(+), 5 deletions(-)
>
> I'm mildly curious: can we just zero out the signature when the
> de-registration / freeing happens? Otherwise, the nested loop added
> below will penalize (performance-wise) correctly written client code as
> well.
>
> > diff --git a/MdeModulePkg/Core/PiSmmCore/Smi.c
> > b/MdeModulePkg/Core/PiSmmCore/Smi.c
> > index ad483a1877ce..6596ea9560d1 100644
> > --- a/MdeModulePkg/Core/PiSmmCore/Smi.c
> > +++ b/MdeModulePkg/Core/PiSmmCore/Smi.c
> > @@ -290,6 +290,7 @@ SmiHandlerUnRegister (
> > SmiEntry = SmiHandler->SmiEntry;
> >
> > RemoveEntryList (&SmiHandler->Link);
> > + SmiHandler->Signature = 0;
> > FreePool (SmiHandler);
> >
> > if (SmiEntry == NULL) {
>
> Generally, if client code violates an interface contract, then the
> called function is not responsible for catching the error and preventing
> undefined behavior. For "quality of service", we can go to certain
> lengths nonetheless, but it should hopefully not hurt valid client code.
>
> For example, I seem to remember that the list data structure
> implementation checks the internal consistency (which can be costly)
> only if a PCD is set to a certain value. Is that right? Is it an option
> here? (If the above zeroing is not good for some reason.)
>
> Anyway, I'm asking mainly for my own education.
>
> Thanks!
> Laszlo
>
> > diff --git a/MdeModulePkg/Core/PiSmmCore/Smi.c
> b/MdeModulePkg/Core/PiSmmCore/Smi.c
> > index ad483a1877..0c09e7fa10 100644
> > --- a/MdeModulePkg/Core/PiSmmCore/Smi.c
> > +++ b/MdeModulePkg/Core/PiSmmCore/Smi.c
> > @@ -1,7 +1,7 @@
> > /** @file
> > SMI management.
> >
> > - Copyright (c) 2009 - 2017, Intel Corporation. All rights reserved.<BR>
> > + Copyright (c) 2009 - 2018, Intel Corporation. All rights reserved.<BR>
> > This program and the accompanying materials are licensed and made
> available
> > under the terms and conditions of the BSD License which accompanies
> this
> > distribution. The full text of the license may be found at
> > @@ -276,14 +276,41 @@ SmiHandlerUnRegister (
> > {
> > SMI_HANDLER *SmiHandler;
> > SMI_ENTRY *SmiEntry;
> > + LIST_ENTRY *EntryLink;
> > + LIST_ENTRY *HandlerLink;
> >
> > - SmiHandler = (SMI_HANDLER *) DispatchHandle;
> > -
> > - if (SmiHandler == NULL) {
> > + if (DispatchHandle == NULL) {
> > return EFI_INVALID_PARAMETER;
> > }
> >
> > - if (SmiHandler->Signature != SMI_HANDLER_SIGNATURE) {
> > + //
> > + // Look for it in root SMI handlers
> > + //
> > + SmiHandler = NULL;
> > + for ( HandlerLink = GetFirstNode (&mRootSmiEntry.SmiHandlers)
> > + ; !IsNull (&mRootSmiEntry.SmiHandlers, HandlerLink) &&
> (SmiHandler != DispatchHandle)
> > + ; HandlerLink = GetNextNode (&mRootSmiEntry.SmiHandlers,
> HandlerLink)
> > + ) {
> > + SmiHandler = CR (HandlerLink, SMI_HANDLER, Link,
> SMI_HANDLER_SIGNATURE);
> > + }
> > +
> > + //
> > + // Look for it in non-root SMI handlers
> > + //
> > + for ( EntryLink = GetFirstNode (&mSmiEntryList)
> > + ; !IsNull (&mSmiEntryList, EntryLink) && (SmiHandler !=
> DispatchHandle)
> > + ; EntryLink = GetNextNode (&mSmiEntryList, EntryLink)
> > + ) {
> > + SmiEntry = CR (EntryLink, SMI_ENTRY, AllEntries,
> SMI_ENTRY_SIGNATURE);
> > + for ( HandlerLink = GetFirstNode (&SmiEntry->SmiHandlers)
> > + ; !IsNull (&SmiEntry->SmiHandlers, HandlerLink) && (SmiHandler !=
> DispatchHandle)
> > + ; HandlerLink = GetNextNode (&SmiEntry->SmiHandlers, HandlerLink)
> > + ) {
> > + SmiHandler = CR (HandlerLink, SMI_HANDLER, Link,
> SMI_HANDLER_SIGNATURE);
> > + }
> > + }
> > +
> > + if (SmiHandler != DispatchHandle) {
> > return EFI_INVALID_PARAMETER;
> > }
> >
> >
>
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> edk2-devel@lists.01.org
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^ permalink raw reply [flat|nested] 4+ messages in thread