Re: [PATCH v2 19/39] mm/mmap: Add shadow stack pages to memory accounting
From: Kirill A . Shutemov <hidden>
Date: 2022-10-04 00:04:03
Also in:
linux-api, linux-arch, linux-mm, lkml
On Thu, Sep 29, 2022 at 03:29:16PM -0700, Rick Edgecombe wrote:
quoted hunk ↗ jump to hunk
From: Yu-cheng Yu <redacted> Account shadow stack pages to stack memory. Signed-off-by: Yu-cheng Yu <redacted> Co-developed-by: Rick Edgecombe <rick.p.edgecombe@intel.com> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com> Cc: Kees Cook <redacted> --- v2: - Remove is_shadow_stack_mapping() and just change it to directly bitwise and VM_SHADOW_STACK. Yu-cheng v26: - Remove redundant #ifdef CONFIG_MMU. Yu-cheng v25: - Remove #ifdef CONFIG_ARCH_HAS_SHADOW_STACK for is_shadow_stack_mapping(). mm/mmap.c | 5 +++++ 1 file changed, 5 insertions(+)diff --git a/mm/mmap.c b/mm/mmap.c index f0d2e9143bd0..8569ef09614c 100644 --- a/mm/mmap.c +++ b/mm/mmap.c@@ -1682,6 +1682,9 @@ static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags) if (file && is_file_hugepages(file)) return 0; + if (vm_flags & VM_SHADOW_STACK) + return 1; + return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
Hm. Isn't the last check true for shadow stack too? IIUC, shadow stack has VM_WRITE set, so accountable_mapping() should work correctly as is. -- Kiryl Shutsemau / Kirill A. Shutemov