> v4 changes: > a. refine PCD description of PcdHeapGuardPropertyMask
UAF (Use-After-Free) memory issue is kind of illegal access to memory which has been freed. It can be detected by a new freed-memory guard enforced onto freed memory. BIT4 of following PCD is used to enable the freed-memory guard feature. gEfiMdeModulePkgTokenSpaceGuid.PcdHeapGuardPropertyMask Please note this feature is for debug purpose and should not be enabled in product BIOS, and cannot be enabled with pool/page heap guard at the same time. It's disabled by default. Cc: Star Zeng <star.z...@intel.com> Cc: Michael D Kinney <michael.d.kin...@intel.com> Cc: Jiewen Yao <jiewen....@intel.com> Cc: Ruiyu Ni <ruiyu...@intel.com> Cc: Laszlo Ersek <ler...@redhat.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Jian J Wang <jian.j.w...@intel.com> --- MdeModulePkg/MdeModulePkg.dec | 16 ++++++++++++---- MdeModulePkg/MdeModulePkg.uni | 14 ++++++++++---- 2 files changed, 22 insertions(+), 8 deletions(-) diff --git a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.dec index 2009dbc5fd..428eeeb670 100644 --- a/MdeModulePkg/MdeModulePkg.dec +++ b/MdeModulePkg/MdeModulePkg.dec @@ -1011,14 +1011,22 @@ gEfiMdeModulePkgTokenSpaceGuid.PcdHeapGuardPoolType|0x0|UINT64|0x30001053 ## This mask is to control Heap Guard behavior. - # Note that due to the limit of pool memory implementation and the alignment - # requirement of UEFI spec, BIT7 is a try-best setting which cannot guarantee - # that the returned pool is exactly adjacent to head guard page or tail guard - # page. + # + # Note: + # a) Heap Guard is for debug purpose and should not be enabled in product + # BIOS. + # b) Due to the limit of pool memory implementation and the alignment + # requirement of UEFI spec, BIT7 is a try-best setting which cannot + # guarantee that the returned pool is exactly adjacent to head guard + # page or tail guard page. + # c) UEFI freed-memory guard and UEFI pool/page guard cannot be enabled + # at the same time. + # # BIT0 - Enable UEFI page guard.<BR> # BIT1 - Enable UEFI pool guard.<BR> # BIT2 - Enable SMM page guard.<BR> # BIT3 - Enable SMM pool guard.<BR> + # BIT4 - Enable UEFI freed-memory guard (Use-After-Free memory detection).<BR> # BIT6 - Enable non-stop mode.<BR> # BIT7 - The direction of Guard Page for Pool Guard. # 0 - The returned pool is near the tail guard page.<BR> diff --git a/MdeModulePkg/MdeModulePkg.uni b/MdeModulePkg/MdeModulePkg.uni index 9d2e473fa9..5fa7a6ae30 100644 --- a/MdeModulePkg/MdeModulePkg.uni +++ b/MdeModulePkg/MdeModulePkg.uni @@ -1224,14 +1224,20 @@ #string STR_gEfiMdeModulePkgTokenSpaceGuid_PcdHeapGuardPropertyMask_PROMPT #language en-US "The Heap Guard feature mask" #string STR_gEfiMdeModulePkgTokenSpaceGuid_PcdHeapGuardPropertyMask_HELP #language en-US "This mask is to control Heap Guard behavior.\n" - "Note that due to the limit of pool memory implementation and the alignment\n" - "requirement of UEFI spec, BIT7 is a try-best setting which cannot guarantee\n" - "that the returned pool is exactly adjacent to head guard page or tail guard\n" - "page.\n" + " Note:\n" + " a) Heap Guard is for debug purpose and should not be enabled in product" + " BIOS.\n" + " b) Due to the limit of pool memory implementation and the alignment" + " requirement of UEFI spec, BIT7 is a try-best setting which cannot" + " guarantee that the returned pool is exactly adjacent to head guard" + " page or tail guard page.\n" + " c) UEFI freed-memory guard and UEFI pool/page guard cannot be enabled" + " at the same time.\n" " BIT0 - Enable UEFI page guard.<BR>\n" " BIT1 - Enable UEFI pool guard.<BR>\n" " BIT2 - Enable SMM page guard.<BR>\n" " BIT3 - Enable SMM pool guard.<BR>\n" + " BIT4 - Enable UEFI freed-memory guard (Use-After-Free memory detection).<BR>\n" " BIT7 - The direction of Guard Page for Pool Guard.\n" " 0 - The returned pool is near the tail guard page.<BR>\n" " 1 - The returned pool is near the head guard page.<BR>" -- 2.16.2.windows.1 _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel