From: tip-bot for Dave Hansen <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: jpoimboe@redhat.com, tglx@linutronix.de, mingo@kernel.org,
bp@alien8.de, jgross@suse.com, hpa@zytor.com,
dave.hansen@linux.intel.com, keescook@chromium.org,
dwmw2@infradead.org, torvalds@linux-foundation.org,
peterz@infradead.org, namit@vmware.com, luto@kernel.org,
dan.j.williams@intel.com, hughd@google.com,
arjan@linux.intel.com, gregkh@linuxfoundation.org,
aarcange@redhat.com, linux-kernel@vger.kernel.org
Subject: [tip:x86/pti] x86/mm: Do not forbid _PAGE_RW before init for __ro_after_init
Date: Thu, 12 Apr 2018 00:15:28 -0700 [thread overview]
Message-ID: <tip-639d6aafe437a7464399d2a77d006049053df06f@git.kernel.org> (raw)
In-Reply-To: <20180406205514.8D898241@viggo.jf.intel.com>
Commit-ID: 639d6aafe437a7464399d2a77d006049053df06f
Gitweb: https://git.kernel.org/tip/639d6aafe437a7464399d2a77d006049053df06f
Author: Dave Hansen <dave.hansen@linux.intel.com>
AuthorDate: Fri, 6 Apr 2018 13:55:14 -0700
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Thu, 12 Apr 2018 09:05:59 +0200
x86/mm: Do not forbid _PAGE_RW before init for __ro_after_init
__ro_after_init data gets stuck in the .rodata section. That's normally
fine because the kernel itself manages the R/W properties.
But, if we run __change_page_attr() on an area which is __ro_after_init,
the .rodata checks will trigger and force the area to be immediately
read-only, even if it is early-ish in boot. This caused problems when
trying to clear the _PAGE_GLOBAL bit for these area in the PTI code:
it cleared _PAGE_GLOBAL like I asked, but also took it up on itself
to clear _PAGE_RW. The kernel then oopses the next time it wrote to
a __ro_after_init data structure.
To fix this, add the kernel_set_to_readonly check, just like we have
for kernel text, just a few lines below in this function.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20180406205514.8D898241@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/mm/pageattr.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 968f51a2e39b..a7324045d87d 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -298,9 +298,11 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
/*
* The .rodata section needs to be read-only. Using the pfn
- * catches all aliases.
+ * catches all aliases. This also includes __ro_after_init,
+ * so do not enforce until kernel_set_to_readonly is true.
*/
- if (within(pfn, __pa_symbol(__start_rodata) >> PAGE_SHIFT,
+ if (kernel_set_to_readonly &&
+ within(pfn, __pa_symbol(__start_rodata) >> PAGE_SHIFT,
__pa_symbol(__end_rodata) >> PAGE_SHIFT))
pgprot_val(forbidden) |= _PAGE_RW;
next prev parent reply other threads:[~2018-04-12 7:15 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-06 20:55 [PATCH 00/11] [v5] Use global pages with PTI Dave Hansen
2018-04-06 20:55 ` [PATCH 01/11] x86/mm: factor out pageattr _PAGE_GLOBAL setting Dave Hansen
2018-04-09 17:11 ` [tip:x86/pti] x86/mm: Factor " tip-bot for Dave Hansen
2018-04-06 20:55 ` [PATCH 02/11] x86/mm: undo double _PAGE_PSE clearing Dave Hansen
2018-04-09 17:12 ` [tip:x86/pti] x86/mm: Undo " tip-bot for Dave Hansen
2018-04-06 20:55 ` [PATCH 03/11] x86/mm: introduce "default" kernel PTE mask Dave Hansen
2018-04-09 17:12 ` [tip:x86/pti] x86/mm: Introduce " tip-bot for Dave Hansen
2018-04-06 20:55 ` [PATCH 04/11] x86/espfix: document use of _PAGE_GLOBAL Dave Hansen
2018-04-09 17:13 ` [tip:x86/pti] x86/espfix: Document " tip-bot for Dave Hansen
2018-04-06 20:55 ` [PATCH 05/11] x86/mm: do not auto-massage page protections Dave Hansen
2018-04-09 17:13 ` [tip:x86/pti] x86/mm: Do " tip-bot for Dave Hansen
2018-04-12 7:13 ` tip-bot for Dave Hansen
2018-04-06 20:55 ` [PATCH 06/11] x86/mm: remove extra filtering in pageattr code Dave Hansen
2018-04-09 17:14 ` [tip:x86/pti] x86/mm: Remove " tip-bot for Dave Hansen
2018-04-12 7:14 ` tip-bot for Dave Hansen
2018-04-06 20:55 ` [PATCH 07/11] x86/mm: comment _PAGE_GLOBAL mystery Dave Hansen
2018-04-09 17:14 ` [tip:x86/pti] x86/mm: Comment " tip-bot for Dave Hansen
2018-04-12 7:14 ` tip-bot for Dave Hansen
2018-04-06 20:55 ` [PATCH 08/11] x86/mm: do not forbid _PAGE_RW before init for __ro_after_init Dave Hansen
2018-04-09 17:15 ` [tip:x86/pti] x86/mm: Do " tip-bot for Dave Hansen
2018-04-12 7:15 ` tip-bot for Dave Hansen [this message]
2018-04-06 20:55 ` [PATCH 09/11] x86/pti: enable global pages for shared areas Dave Hansen
2018-04-09 17:15 ` [tip:x86/pti] x86/pti: Enable " tip-bot for Dave Hansen
2018-04-12 7:15 ` tip-bot for Dave Hansen
2018-04-06 20:55 ` [PATCH 10/11] x86/pti: never implicitly clear _PAGE_GLOBAL for kernel image Dave Hansen
2018-04-09 17:16 ` [tip:x86/pti] x86/pti: Never " tip-bot for Dave Hansen
2018-04-12 7:16 ` tip-bot for Dave Hansen
2018-04-06 20:55 ` [PATCH 11/11] x86/pti: leave kernel text global for !PCID Dave Hansen
2018-04-09 17:16 ` [tip:x86/pti] x86/pti: Leave " tip-bot for Dave Hansen
2018-04-12 7:17 ` tip-bot for Dave Hansen
2018-04-19 0:11 ` [PATCH 11/11] x86/pti: leave " Kees Cook
2018-04-19 16:02 ` Dave Hansen
2018-04-19 16:55 ` Kees Cook
2018-04-09 18:04 ` [PATCH 00/11] [v5] Use global pages with PTI Tom Lendacky
2018-04-09 18:17 ` Dave Hansen
2018-04-09 18:59 ` Tom Lendacky
2018-04-09 19:50 ` Dave Hansen
2018-04-09 20:48 ` Tom Lendacky
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