Re: [RFC PATCH v2 15/27] mm/mprotect: Prevent mprotect from changing shadow stack
From: Dave Hansen <dave.hansen@linux.intel.com>
Date: 2018-07-10 23:10:12
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linux-arch, linux-doc, linux-mm, lkml
On 07/10/2018 03:26 PM, Yu-cheng Yu wrote:
Signed-off-by: Yu-cheng Yu <redacted>
This still needs a changelog, even if you think it's simple.
quoted hunk ↗ jump to hunk
--- a/mm/mprotect.c +++ b/mm/mprotect.c@@ -446,6 +446,15 @@ static int do_mprotect_pkey(unsigned long start, size_t len, error = -ENOMEM; if (!vma) goto out; + + /* + * Do not allow changing shadow stack memory. + */ + if (vma->vm_flags & VM_SHSTK) { + error = -EINVAL; + goto out; + } +
I think this is a _bit_ draconian. Why shouldn't we be able to use protection keys with a shadow stack? Or, set it to PROT_NONE?