UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c | 40 ++++++++++++++++++++++++++++------------ 1 file changed, 28 insertions(+), 12 deletions(-)
When setting new page table pool to RO, only disable/enable WP when
Cr0.WP has been set to 1 to fix potential PF caused by b822be1a20
(UefiCpuPkg/PiSmmCpuDxeSmm: Introduce page table pool mechanism).
With previous code, if someone want to modify the page table and
Cr0.WP has been cleared before modify page table, Cr0.WP may be set
to 1 again since new pool may be generated during this process
Then PF fault may happens.
Signed-off-by: Dun Tan <dun.tan@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
---
UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c | 40 ++++++++++++++++++++++++++++------------
1 file changed, 28 insertions(+), 12 deletions(-)
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
index 4bb23f6920..c385f12d9c 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c
@@ -67,8 +67,10 @@ InitializePageTablePool (
IN UINTN PoolPages
)
{
- VOID *Buffer;
- BOOLEAN CetEnabled;
+ VOID *Buffer;
+ BOOLEAN CetEnabled;
+ BOOLEAN WpEnabled;
+ IA32_CR0 Cr0;
//
// Always reserve at least PAGE_TABLE_POOL_UNIT_PAGES, including one page for
@@ -106,21 +108,35 @@ InitializePageTablePool (
//
if (mIsReadOnlyPageTable) {
CetEnabled = ((AsmReadCr4 () & CR4_CET_ENABLE) != 0) ? TRUE : FALSE;
- if (CetEnabled) {
+ Cr0.UintN = AsmReadCr0 ();
+ WpEnabled = (Cr0.Bits.WP != 0) ? TRUE : FALSE;
+ if (WpEnabled) {
//
- // CET must be disabled if WP is disabled.
+ // Only disable/enable WP when Cr0.Bits.WP has been set to 1.
//
- DisableCet ();
+ Cr0.Bits.WP = 0;
+ AsmWriteCr0 (Cr0.UintN);
+
+ if (CetEnabled) {
+ //
+ // CET must be disabled if WP is disabled.
+ //
+ DisableCet ();
+ }
}
- AsmWriteCr0 (AsmReadCr0 () & ~CR0_WP);
SmmSetMemoryAttributes ((EFI_PHYSICAL_ADDRESS)(UINTN)Buffer, EFI_PAGES_TO_SIZE (PoolPages), EFI_MEMORY_RO);
- AsmWriteCr0 (AsmReadCr0 () | CR0_WP);
- if (CetEnabled) {
- //
- // re-enable CET.
- //
- EnableCet ();
+ if (WpEnabled) {
+ Cr0.UintN = AsmReadCr0 ();
+ Cr0.Bits.WP = 1;
+ AsmWriteCr0 (Cr0.UintN);
+
+ if (CetEnabled) {
+ //
+ // re-enable CET.
+ //
+ EnableCet ();
+ }
}
}
--
2.31.1.windows.1
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Dun, CET should be disabled before clearing CR0.WP. > -----Original Message----- > From: Tan, Dun <dun.tan@intel.com> > Sent: Tuesday, January 3, 2023 10:57 AM > To: devel@edk2.groups.io > Cc: Dong, Eric <eric.dong@intel.com>; Ni, Ray <ray.ni@intel.com>; Kumar, Rahul R <rahul.r.kumar@intel.com> > Subject: [PATCH] UefiCpuPkg/PiSmmCpuDxeSmm:Fix PF issue caused by smm page table code > > When setting new page table pool to RO, only disable/enable WP when > Cr0.WP has been set to 1 to fix potential PF caused by b822be1a20 > (UefiCpuPkg/PiSmmCpuDxeSmm: Introduce page table pool mechanism). > With previous code, if someone want to modify the page table and > Cr0.WP has been cleared before modify page table, Cr0.WP may be set > to 1 again since new pool may be generated during this process > Then PF fault may happens. > > Signed-off-by: Dun Tan <dun.tan@intel.com> > Cc: Eric Dong <eric.dong@intel.com> > Cc: Ray Ni <ray.ni@intel.com> > Cc: Rahul Kumar <rahul1.kumar@intel.com> > --- > UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c | 40 ++++++++++++++++++++++++++++------------ > 1 file changed, 28 insertions(+), 12 deletions(-) > > diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c > b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c > index 4bb23f6920..c385f12d9c 100644 > --- a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c > @@ -67,8 +67,10 @@ InitializePageTablePool ( > IN UINTN PoolPages > ) > { > - VOID *Buffer; > - BOOLEAN CetEnabled; > + VOID *Buffer; > + BOOLEAN CetEnabled; > + BOOLEAN WpEnabled; > + IA32_CR0 Cr0; > > // > // Always reserve at least PAGE_TABLE_POOL_UNIT_PAGES, including one page for > @@ -106,21 +108,35 @@ InitializePageTablePool ( > // > if (mIsReadOnlyPageTable) { > CetEnabled = ((AsmReadCr4 () & CR4_CET_ENABLE) != 0) ? TRUE : FALSE; > - if (CetEnabled) { > + Cr0.UintN = AsmReadCr0 (); > + WpEnabled = (Cr0.Bits.WP != 0) ? TRUE : FALSE; > + if (WpEnabled) { > // > - // CET must be disabled if WP is disabled. > + // Only disable/enable WP when Cr0.Bits.WP has been set to 1. > // > - DisableCet (); > + Cr0.Bits.WP = 0; > + AsmWriteCr0 (Cr0.UintN); > + > + if (CetEnabled) { > + // > + // CET must be disabled if WP is disabled. > + // > + DisableCet (); > + } > } > > - AsmWriteCr0 (AsmReadCr0 () & ~CR0_WP); > SmmSetMemoryAttributes ((EFI_PHYSICAL_ADDRESS)(UINTN)Buffer, EFI_PAGES_TO_SIZE (PoolPages), > EFI_MEMORY_RO); > - AsmWriteCr0 (AsmReadCr0 () | CR0_WP); > - if (CetEnabled) { > - // > - // re-enable CET. > - // > - EnableCet (); > + if (WpEnabled) { > + Cr0.UintN = AsmReadCr0 (); > + Cr0.Bits.WP = 1; > + AsmWriteCr0 (Cr0.UintN); > + > + if (CetEnabled) { > + // > + // re-enable CET. > + // > + EnableCet (); > + } > } > } > > -- > 2.31.1.windows.1 -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#97852): https://edk2.groups.io/g/devel/message/97852 Mute This Topic: https://groups.io/mt/96022133/1787277 Group Owner: devel+owner@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [importer@patchew.org] -=-=-=-=-=-=-=-=-=-=-=-
Ray, Thanks for the comments. Will send V2 patch soon. Thanks, Dun -----Original Message----- From: Ni, Ray <ray.ni@intel.com> Sent: Tuesday, January 3, 2023 11:23 AM To: Tan, Dun <dun.tan@intel.com>; devel@edk2.groups.io Cc: Dong, Eric <eric.dong@intel.com>; Kumar, Rahul R <rahul.r.kumar@intel.com> Subject: RE: [PATCH] UefiCpuPkg/PiSmmCpuDxeSmm:Fix PF issue caused by smm page table code Dun, CET should be disabled before clearing CR0.WP. > -----Original Message----- > From: Tan, Dun <dun.tan@intel.com> > Sent: Tuesday, January 3, 2023 10:57 AM > To: devel@edk2.groups.io > Cc: Dong, Eric <eric.dong@intel.com>; Ni, Ray <ray.ni@intel.com>; > Kumar, Rahul R <rahul.r.kumar@intel.com> > Subject: [PATCH] UefiCpuPkg/PiSmmCpuDxeSmm:Fix PF issue caused by smm > page table code > > When setting new page table pool to RO, only disable/enable WP when > Cr0.WP has been set to 1 to fix potential PF caused by b822be1a20 > (UefiCpuPkg/PiSmmCpuDxeSmm: Introduce page table pool mechanism). > With previous code, if someone want to modify the page table and > Cr0.WP has been cleared before modify page table, Cr0.WP may be set to > 1 again since new pool may be generated during this process Then PF > fault may happens. > > Signed-off-by: Dun Tan <dun.tan@intel.com> > Cc: Eric Dong <eric.dong@intel.com> > Cc: Ray Ni <ray.ni@intel.com> > Cc: Rahul Kumar <rahul1.kumar@intel.com> > --- > UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c | 40 > ++++++++++++++++++++++++++++------------ > 1 file changed, 28 insertions(+), 12 deletions(-) > > diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c > b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c > index 4bb23f6920..c385f12d9c 100644 > --- a/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c > +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/SmmCpuMemoryManagement.c > @@ -67,8 +67,10 @@ InitializePageTablePool ( > IN UINTN PoolPages > ) > { > - VOID *Buffer; > - BOOLEAN CetEnabled; > + VOID *Buffer; > + BOOLEAN CetEnabled; > + BOOLEAN WpEnabled; > + IA32_CR0 Cr0; > > // > // Always reserve at least PAGE_TABLE_POOL_UNIT_PAGES, including > one page for @@ -106,21 +108,35 @@ InitializePageTablePool ( > // > if (mIsReadOnlyPageTable) { > CetEnabled = ((AsmReadCr4 () & CR4_CET_ENABLE) != 0) ? TRUE : FALSE; > - if (CetEnabled) { > + Cr0.UintN = AsmReadCr0 (); > + WpEnabled = (Cr0.Bits.WP != 0) ? TRUE : FALSE; > + if (WpEnabled) { > // > - // CET must be disabled if WP is disabled. > + // Only disable/enable WP when Cr0.Bits.WP has been set to 1. > // > - DisableCet (); > + Cr0.Bits.WP = 0; > + AsmWriteCr0 (Cr0.UintN); > + > + if (CetEnabled) { > + // > + // CET must be disabled if WP is disabled. > + // > + DisableCet (); > + } > } > > - AsmWriteCr0 (AsmReadCr0 () & ~CR0_WP); > SmmSetMemoryAttributes ((EFI_PHYSICAL_ADDRESS)(UINTN)Buffer, > EFI_PAGES_TO_SIZE (PoolPages), EFI_MEMORY_RO); > - AsmWriteCr0 (AsmReadCr0 () | CR0_WP); > - if (CetEnabled) { > - // > - // re-enable CET. > - // > - EnableCet (); > + if (WpEnabled) { > + Cr0.UintN = AsmReadCr0 (); > + Cr0.Bits.WP = 1; > + AsmWriteCr0 (Cr0.UintN); > + > + if (CetEnabled) { > + // > + // re-enable CET. > + // > + EnableCet (); > + } > } > } > > -- > 2.31.1.windows.1 -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#97853): https://edk2.groups.io/g/devel/message/97853 Mute This Topic: https://groups.io/mt/96022133/1787277 Group Owner: devel+owner@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [importer@patchew.org] -=-=-=-=-=-=-=-=-=-=-=-
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