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回复: [edk2-devel] [PATCH v1 1/1] MdeModulePkg: PiSmmCore: Inspect memory guarded with pool headers

gaoliming

Reviewed-by: Liming Gao <gaoliming@...>

Show quoted text

-----邮件原件-----
发件人: devel@edk2.groups.io <devel@edk2.groups.io> 代表 Kun Qin
发送时间: 2022年3月16日 12:00
收件人: devel@edk2.groups.io
抄送: Jiewen Yao <jiewen.yao@...>; Eric Dong <eric.dong@...>;
Ray Ni <ray.ni@...>; Jian J Wang <jian.j.wang@...>; Liming Gao
<gaoliming@...>
主题: [edk2-devel] [PATCH v1 1/1] MdeModulePkg: PiSmmCore: Inspect
memory guarded with pool headers

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3488

Current free pool routine from PiSmmCore will inspect memory guard status
for target buffer without considering pool headers. This could lead to
`IsMemoryGuarded` function to return incorrect results.

In that sense, allocating a 0 sized pool could cause an allocated buffer
directly points into a guard page, which is legal. However, trying to
free this pool will cause the routine changed in this commit to read XP
pages, which leads to page fault.

This change will inspect memory guarded with pool headers. This can avoid
errors when a pool content happens to be on a page boundary.

Cc: Jiewen Yao <jiewen.yao@...>
Cc: Eric Dong <eric.dong@...>
Cc: Ray Ni <ray.ni@...>
Cc: Jian J Wang <jian.j.wang@...>
Cc: Liming Gao <gaoliming@...>

Signed-off-by: Kun Qin <kuqin12@...>
---
 MdeModulePkg/Core/PiSmmCore/Pool.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/MdeModulePkg/Core/PiSmmCore/Pool.c
b/MdeModulePkg/Core/PiSmmCore/Pool.c
index 96ebe811c669..e1ff40a8ea55 100644
--- a/MdeModulePkg/Core/PiSmmCore/Pool.c
+++ b/MdeModulePkg/Core/PiSmmCore/Pool.c
@@ -382,11 +382,6 @@ SmmInternalFreePool (
     return EFI_INVALID_PARAMETER;
   }

-  MemoryGuarded = IsHeapGuardEnabled () &&
-                  IsMemoryGuarded
((EFI_PHYSICAL_ADDRESS)(UINTN)Buffer);
-  HasPoolTail = !(MemoryGuarded &&
-                  ((PcdGet8 (PcdHeapGuardPropertyMask) & BIT7) ==
0));
-
   FreePoolHdr = (FREE_POOL_HEADER *)((POOL_HEADER *)Buffer - 1);
   ASSERT (FreePoolHdr->Header.Signature == POOL_HEAD_SIGNATURE);
   ASSERT (!FreePoolHdr->Header.Available);
@@ -394,6 +389,11 @@ SmmInternalFreePool (
     return EFI_INVALID_PARAMETER;
   }

+  MemoryGuarded = IsHeapGuardEnabled () &&
+                  IsMemoryGuarded
((EFI_PHYSICAL_ADDRESS)(UINTN)FreePoolHdr);
+  HasPoolTail = !(MemoryGuarded &&
+                  ((PcdGet8 (PcdHeapGuardPropertyMask) & BIT7) ==
0));
+
   if (HasPoolTail) {
     PoolTail = HEAD_TO_TAIL (&FreePoolHdr->Header);
     ASSERT (PoolTail->Signature == POOL_TAIL_SIGNATURE);
--
2.35.1.windows.2

Kun Qin

#88141

Thanks, Liming.

SMM owners/authors,

Could you please also review the original issue and this patch to provide feedback?

Thanks,
Kun

Show quoted text

On 3/17/2022 6:20 PM, gaoliming wrote:
Reviewed-by: Liming Gao <gaoliming@...>

-----邮件原件-----
发件人: devel@edk2.groups.io <devel@edk2.groups.io> 代表 Kun Qin
发送时间: 2022年3月16日 12:00
收件人: devel@edk2.groups.io
抄送: Jiewen Yao <jiewen.yao@...>; Eric Dong <eric.dong@...>;
Ray Ni <ray.ni@...>; Jian J Wang <jian.j.wang@...>; Liming Gao
<gaoliming@...>
主题: [edk2-devel] [PATCH v1 1/1] MdeModulePkg: PiSmmCore: Inspect
memory guarded with pool headers

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3488

Current free pool routine from PiSmmCore will inspect memory guard status
for target buffer without considering pool headers. This could lead to
`IsMemoryGuarded` function to return incorrect results.

In that sense, allocating a 0 sized pool could cause an allocated buffer
directly points into a guard page, which is legal. However, trying to
free this pool will cause the routine changed in this commit to read XP
pages, which leads to page fault.

This change will inspect memory guarded with pool headers. This can avoid
errors when a pool content happens to be on a page boundary.

Cc: Jiewen Yao <jiewen.yao@...>
Cc: Eric Dong <eric.dong@...>
Cc: Ray Ni <ray.ni@...>
Cc: Jian J Wang <jian.j.wang@...>
Cc: Liming Gao <gaoliming@...>

Signed-off-by: Kun Qin <kuqin12@...>
---
  MdeModulePkg/Core/PiSmmCore/Pool.c | 10 +++++-----
  1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/MdeModulePkg/Core/PiSmmCore/Pool.c
b/MdeModulePkg/Core/PiSmmCore/Pool.c
index 96ebe811c669..e1ff40a8ea55 100644
--- a/MdeModulePkg/Core/PiSmmCore/Pool.c
+++ b/MdeModulePkg/Core/PiSmmCore/Pool.c
@@ -382,11 +382,6 @@ SmmInternalFreePool (
      return EFI_INVALID_PARAMETER;
    }

-  MemoryGuarded = IsHeapGuardEnabled () &&
-                  IsMemoryGuarded
((EFI_PHYSICAL_ADDRESS)(UINTN)Buffer);
-  HasPoolTail = !(MemoryGuarded &&
-                  ((PcdGet8 (PcdHeapGuardPropertyMask) & BIT7) ==
0));
-
    FreePoolHdr = (FREE_POOL_HEADER *)((POOL_HEADER *)Buffer - 1);
    ASSERT (FreePoolHdr->Header.Signature == POOL_HEAD_SIGNATURE);
    ASSERT (!FreePoolHdr->Header.Available);
@@ -394,6 +389,11 @@ SmmInternalFreePool (
      return EFI_INVALID_PARAMETER;
    }

+  MemoryGuarded = IsHeapGuardEnabled () &&
+                  IsMemoryGuarded
((EFI_PHYSICAL_ADDRESS)(UINTN)FreePoolHdr);
+  HasPoolTail = !(MemoryGuarded &&
+                  ((PcdGet8 (PcdHeapGuardPropertyMask) & BIT7) ==
0));
+
    if (HasPoolTail) {
      PoolTail = HEAD_TO_TAIL (&FreePoolHdr->Header);
      ASSERT (PoolTail->Signature == POOL_TAIL_SIGNATURE);
--
2.35.1.windows.2

Kun Qin

#89197

Hi SMM maintainers,

A gentle ping on this. Could you please provide some feedback on the fix below for allocating 0 sized pool when heap guard it on?

Thanks in advance,
Kun

Show quoted text

On 3/28/2022 2:57 PM, Kun Qin wrote:
Thanks, Liming.

SMM owners/authors,

Could you please also review the original issue and this patch to provide feedback?

Thanks,
Kun

On 3/17/2022 6:20 PM, gaoliming wrote:
Reviewed-by: Liming Gao <gaoliming@...>

-----邮件原件-----
发件人: devel@edk2.groups.io <devel@edk2.groups.io> 代表 Kun Qin
发送时间: 2022年3月16日 12:00
收件人: devel@edk2.groups.io
抄送: Jiewen Yao <jiewen.yao@...>; Eric Dong <eric.dong@...>;
Ray Ni <ray.ni@...>; Jian J Wang <jian.j.wang@...>; Liming Gao
<gaoliming@...>
主题: [edk2-devel] [PATCH v1 1/1] MdeModulePkg: PiSmmCore: Inspect
memory guarded with pool headers

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3488

Current free pool routine from PiSmmCore will inspect memory guard status
for target buffer without considering pool headers. This could lead to
`IsMemoryGuarded` function to return incorrect results.

In that sense, allocating a 0 sized pool could cause an allocated buffer
directly points into a guard page, which is legal. However, trying to
free this pool will cause the routine changed in this commit to read XP
pages, which leads to page fault.

This change will inspect memory guarded with pool headers. This can avoid
errors when a pool content happens to be on a page boundary.

Cc: Jiewen Yao <jiewen.yao@...>
Cc: Eric Dong <eric.dong@...>
Cc: Ray Ni <ray.ni@...>
Cc: Jian J Wang <jian.j.wang@...>
Cc: Liming Gao <gaoliming@...>

Signed-off-by: Kun Qin <kuqin12@...>
---
  MdeModulePkg/Core/PiSmmCore/Pool.c | 10 +++++-----
  1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/MdeModulePkg/Core/PiSmmCore/Pool.c
b/MdeModulePkg/Core/PiSmmCore/Pool.c
index 96ebe811c669..e1ff40a8ea55 100644
--- a/MdeModulePkg/Core/PiSmmCore/Pool.c
+++ b/MdeModulePkg/Core/PiSmmCore/Pool.c
@@ -382,11 +382,6 @@ SmmInternalFreePool (
      return EFI_INVALID_PARAMETER;
    }

-  MemoryGuarded = IsHeapGuardEnabled () &&
-                  IsMemoryGuarded
((EFI_PHYSICAL_ADDRESS)(UINTN)Buffer);
-  HasPoolTail = !(MemoryGuarded &&
-                  ((PcdGet8 (PcdHeapGuardPropertyMask) & BIT7) ==
0));
-
    FreePoolHdr = (FREE_POOL_HEADER *)((POOL_HEADER *)Buffer - 1);
    ASSERT (FreePoolHdr->Header.Signature == POOL_HEAD_SIGNATURE);
    ASSERT (!FreePoolHdr->Header.Available);
@@ -394,6 +389,11 @@ SmmInternalFreePool (
      return EFI_INVALID_PARAMETER;
    }

+  MemoryGuarded = IsHeapGuardEnabled () &&
+                  IsMemoryGuarded
((EFI_PHYSICAL_ADDRESS)(UINTN)FreePoolHdr);
+  HasPoolTail = !(MemoryGuarded &&
+                  ((PcdGet8 (PcdHeapGuardPropertyMask) & BIT7) ==
0));
+
    if (HasPoolTail) {
      PoolTail = HEAD_TO_TAIL (&FreePoolHdr->Header);
      ASSERT (PoolTail->Signature == POOL_TAIL_SIGNATURE);
-- 
2.35.1.windows.2

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