From mboxrd@z Thu Jan 1 00:00:00 1970 Reply-To: kernel-hardening@lists.openwall.com From: Andy Lutomirski Date: Wed, 15 Jun 2016 17:28:25 -0700 Message-Id: <3336bb02792d56c49d18e2f7a435fd194a4a22e4.1466036668.git.luto@kernel.org> In-Reply-To: References: In-Reply-To: References: Subject: [kernel-hardening] [PATCH 03/13] x86/cpa: Warn if kernel_unmap_pages_in_pgd is used inappropriately To: "linux-kernel@vger.kernel.org" , x86@kernel.org, Borislav Petkov Cc: Nadav Amit , Kees Cook , Brian Gerst , "kernel-hardening@lists.openwall.com" , Linus Torvalds , Josh Poimboeuf , Andy Lutomirski List-ID: 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 --- 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