Messages in this thread Patch in this message | | | From | Lai Jiangshan <> | Subject | [PATCH V2 2/3] x86/mm/pti: issue warning when mapping large pmd beyond specifid range | Date | Thu, 10 Dec 2020 22:35:25 +0800 |
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From: Lai Jiangshan <laijs@linux.alibaba.com>
When PTI_CLONE_PTE, the caller doesn't want to expose pages beyond specifid range and it worths a warning.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com> --- arch/x86/mm/pti.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c index 7ee99ef13a99..cd6da1d42ba9 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -356,6 +356,13 @@ pti_clone_pgtable(unsigned long start, unsigned long end, * caller, so we just simply align it here. */ addr = round_down(addr, PMD_SIZE); + /* + * Mapping large pmd beyond [start, end) may expose + * secrets to user-space when it wants to clone ptes + * only. + */ + WARN_ON_ONCE(level == PTI_CLONE_PTE && + (addr < start || end < addr + PMD_SIZE)); target_pmd = pti_user_pagetable_walk_pmd(addr); if (WARN_ON(!target_pmd)) -- 2.19.1.6.gb485710b
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