diff options
| author | Andrey Ryabinin <[email protected]> | 2018-06-25 13:24:27 +0300 |
|---|---|---|
| committer | Ingo Molnar <[email protected]> | 2018-06-26 09:21:48 +0200 |
| commit | 0e311d237d7f3022b7dafb639b42541bfb42fe94 (patch) | |
| tree | e85cd99eb616208781f58e1f9034f3d752f60639 | |
| parent | 236f0cd286b67291796362feeac4f342900cfa82 (diff) | |
x86/mm: Don't free P4D table when it is folded at runtime
When the P4D page table layer is folded at runtime, the p4d_free()
should do nothing, the same as in <asm-generic/pgtable-nop4d.h>.
It seems this bug should cause double-free in efi_call_phys_epilog(),
but I don't know how to trigger that code path, so I can't confirm that
by testing.
Signed-off-by: Andrey Ryabinin <[email protected]>
Reviewed-by: Kirill A. Shutemov <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected] # 4.17
Fixes: 98219dda2ab5 ("x86/mm: Fold p4d page table layer at runtime")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
| -rw-r--r-- | arch/x86/include/asm/pgalloc.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/x86/include/asm/pgalloc.h b/arch/x86/include/asm/pgalloc.h index ada6410fd2ec..fbd578daa66e 100644 --- a/arch/x86/include/asm/pgalloc.h +++ b/arch/x86/include/asm/pgalloc.h @@ -184,6 +184,9 @@ static inline p4d_t *p4d_alloc_one(struct mm_struct *mm, unsigned long addr) static inline void p4d_free(struct mm_struct *mm, p4d_t *p4d) { + if (!pgtable_l5_enabled()) + return; + BUG_ON((unsigned long)p4d & (PAGE_SIZE-1)); free_page((unsigned long)p4d); } |