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linguini1 pushed a commit to branch releases/13.0
in repository https://gitbox.apache.org/repos/asf/nuttx.git
The following commit(s) were added to refs/heads/releases/13.0 by this push:
new 804249a0b27 arch/x86_64: fix page table levels in pgalloc
804249a0b27 is described below
commit 804249a0b2740ec32b2c07e2e66da716ceeff855
Author: raiden00pl <[email protected]>
AuthorDate: Tue Aug 4 21:37:03 2026 +0200
arch/x86_64: fix page table levels in pgalloc
Two level errors corrupted kernel memory when a user process extended
its heap with sbrk:
- PGT_LAST was X86_MMU_PT_LEVELS (4), but valid levels are 0-3, so the
final level entry was written with an out-of-range index.
- x86_64_get_pgtable indexed the PD (level 2) with level 3, installing
newly allocated page tables into the wrong PD slot.
Signed-off-by: raiden00pl <[email protected]>
Assisted-by: Claude Code
---
arch/x86_64/src/common/x86_64_pgalloc.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86_64/src/common/x86_64_pgalloc.c
b/arch/x86_64/src/common/x86_64_pgalloc.c
index bbe90a96995..084bcf2cb3b 100644
--- a/arch/x86_64/src/common/x86_64_pgalloc.c
+++ b/arch/x86_64/src/common/x86_64_pgalloc.c
@@ -50,7 +50,7 @@
/* Last PGT level */
-#define PGT_LAST (X86_MMU_PT_LEVELS)
+#define PGT_LAST (X86_MMU_PT_LEVELS - 1)
/****************************************************************************
* Private Functions
@@ -82,7 +82,7 @@ uintptr_t x86_64_get_pgtable(arch_addrenv_t *addrenv,
uintptr_t vaddr)
/* Get the current level MAX_LEVELS-1 entry corresponding to this vaddr */
- ptlevel = ARCH_SPGTS;
+ ptlevel = ARCH_SPGTS - 1;
ptprev = x86_64_pgvaddr(addrenv->spgtables[ARCH_SPGTS - 1]);
if (!ptprev)
{
