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| author | Vit Kabele <vit@kabele.me> | 2022-02-11 14:01:55 +0200 |
|---|---|---|
| committer | Vit Kabele <vit@kabele.me> | 2022-05-03 14:37:08 +0200 |
| commit | cc9e7763ceb2e2649fe3422130416d84a3c6854a (patch) | |
| tree | 603e8cb04c87df79842fa51495c88ebd3acca531 | |
| parent | c6837a4aaeb4b7f6000307aacc04de99d1bae28c (diff) | |
| download | acpica-cc9e7763ceb2e2649fe3422130416d84a3c6854a.tar.gz | |
Check that EBDA pointer is in valid memory
If the memory at 0x40e is uninitialized, the retrieved physical_memory
address of EBDA may be beyond the low memory (i.e. above 640K).
If so, the kernel may unintentionally access the VGA memory, that
might not be decoded or even present in case of virtualization.
Signed-off-by: Vit Kabele <vit@kabele.me>
| -rw-r--r-- | source/components/tables/tbxfroot.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/source/components/tables/tbxfroot.c b/source/components/tables/tbxfroot.c index bb90f6059..271c9424d 100644 --- a/source/components/tables/tbxfroot.c +++ b/source/components/tables/tbxfroot.c @@ -299,7 +299,12 @@ AcpiFindRootPointer ( /* EBDA present? */ - if (PhysicalAddress > 0x400) + /* + * Check that the EBDA pointer from memory is sane and does not point + * above valid low memory + */ + if (PhysicalAddress > 0x400 && + PhysicalAddress < 0xA0000) { /* * 1b) Search EBDA paragraphs (EBDA is required to be a |