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| author | Kun Qin <kuqin@microsoft.com> | 2024-07-16 15:50:01 -0700 |
|---|---|---|
| committer | mergify[bot] <37929162+mergify[bot]@users.noreply.github.com> | 2024-07-17 20:56:50 +0000 |
| commit | cee9d1b16bdcd7fe8bad6b39fe18af0a15941ca4 (patch) | |
| tree | 3f963e0aaafce89287f8c8dcd9ea181d668c7f91 /MdeModulePkg/Core/Dxe | |
| parent | 0adc868b362873eb7c749f3ac6c38f9e293af10d (diff) | |
| download | edk2-cee9d1b16bdcd7fe8bad6b39fe18af0a15941ca4.tar.gz edk2-cee9d1b16bdcd7fe8bad6b39fe18af0a15941ca4.tar.bz2 edk2-cee9d1b16bdcd7fe8bad6b39fe18af0a15941ca4.zip | |
MdeModulePkg: DxeCore: Fix Use-After-Free guard causing page fault
REF:https://bugzilla.tianocore.org/show_bug.cgi?id=2411
With Use-After-Free heap guard feature enabled, the DxeCore would blindly
attempt to "level-up" when the `GuardAllFreedPages` inspect a non-max
level table entry from the last loop. This could cause the next round of
inspection to dereference a potentially null pointer and as such causing
a page fault.
This change adds a null pointer check to prevent such case from happening.
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Signed-off-by: Kun Qin <kun.qin@microsoft.com>
Diffstat (limited to 'MdeModulePkg/Core/Dxe')
| -rw-r--r-- | MdeModulePkg/Core/Dxe/Mem/HeapGuard.c | 51 |
1 files changed, 28 insertions, 23 deletions
diff --git a/MdeModulePkg/Core/Dxe/Mem/HeapGuard.c b/MdeModulePkg/Core/Dxe/Mem/HeapGuard.c index 0c0ca61872..4071053036 100644 --- a/MdeModulePkg/Core/Dxe/Mem/HeapGuard.c +++ b/MdeModulePkg/Core/Dxe/Mem/HeapGuard.c @@ -1406,34 +1406,39 @@ GuardAllFreedPages ( TableEntry = ((UINT64 *)(UINTN)(Tables[Level]))[Indices[Level]];
Address = Addresses[Level];
- if (Level < GUARDED_HEAP_MAP_TABLE_DEPTH - 1) {
- Level += 1;
- Tables[Level] = TableEntry;
- Addresses[Level] = Address;
- Indices[Level] = 0;
-
- continue;
+ if (TableEntry == 0) {
+ GuardPageNumber = 0;
+ GuardPage = (UINT64)-1;
} else {
- BitIndex = 1;
- while (BitIndex != 0) {
- if ((TableEntry & BitIndex) != 0) {
- if (GuardPage == (UINT64)-1) {
- GuardPage = Address;
+ if (Level < GUARDED_HEAP_MAP_TABLE_DEPTH - 1) {
+ Level += 1;
+ Tables[Level] = TableEntry;
+ Addresses[Level] = Address;
+ Indices[Level] = 0;
+
+ continue;
+ } else {
+ BitIndex = 1;
+ while (BitIndex != 0) {
+ if ((TableEntry & BitIndex) != 0) {
+ if (GuardPage == (UINT64)-1) {
+ GuardPage = Address;
+ }
+
+ ++GuardPageNumber;
+ } else if (GuardPageNumber > 0) {
+ GuardFreedPages (GuardPage, GuardPageNumber);
+ GuardPageNumber = 0;
+ GuardPage = (UINT64)-1;
}
- ++GuardPageNumber;
- } else if (GuardPageNumber > 0) {
- GuardFreedPages (GuardPage, GuardPageNumber);
- GuardPageNumber = 0;
- GuardPage = (UINT64)-1;
- }
+ if (TableEntry == 0) {
+ break;
+ }
- if (TableEntry == 0) {
- break;
+ Address += EFI_PAGES_TO_SIZE (1);
+ BitIndex = LShiftU64 (BitIndex, 1);
}
-
- Address += EFI_PAGES_TO_SIZE (1);
- BitIndex = LShiftU64 (BitIndex, 1);
}
}
}
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