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Message-Id: <3336bb02792d56c49d18e2f7a435fd194a4a22e4.1466036668.git.luto@kernel.org>
Date: Wed, 15 Jun 2016 17:28:25 -0700
From: Andy Lutomirski <luto@...nel.org>
To: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
x86@...nel.org,
Borislav Petkov <bp@...en8.de>
Cc: Nadav Amit <nadav.amit@...il.com>,
Kees Cook <keescook@...omium.org>,
Brian Gerst <brgerst@...il.com>,
"kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Andy Lutomirski <luto@...nel.org>
Subject: [PATCH 03/13] x86/cpa: Warn if kernel_unmap_pages_in_pgd is used inappropriately
It's currently only used in the EFI code, which is safe AFAICT.
Warn if anyone tries to use it on the normal kernel pgd.
Signed-off-by: Andy Lutomirski <luto@...nel.org>
---
arch/x86/mm/pageattr.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 6a8026918bf6..e9b9c5cedbb8 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -1996,6 +1996,9 @@ out:
void kernel_unmap_pages_in_pgd(pgd_t *root, unsigned long address,
unsigned numpages)
{
+ /* Unmapping kernel entries from init_mm's pgd is not allowed. */
+ WARN_ON(root == init_mm.pgd);
+
unmap_pgd_range(root, address, address + (numpages << PAGE_SHIFT));
}
--
2.7.4
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