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Commit | Line | Data |
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59d5af67 | 1 | From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 |
321d628a FG |
2 | From: Thomas Gleixner <tglx@linutronix.de> |
3 | Date: Sat, 16 Dec 2017 01:14:39 +0100 | |
59d5af67 | 4 | Subject: [PATCH] x86/mm/dump_pagetables: Check PAGE_PRESENT for real |
321d628a FG |
5 | MIME-Version: 1.0 |
6 | Content-Type: text/plain; charset=UTF-8 | |
7 | Content-Transfer-Encoding: 8bit | |
8 | ||
9 | CVE-2017-5754 | |
10 | ||
11 | The check for a present page in printk_prot(): | |
12 | ||
13 | if (!pgprot_val(prot)) { | |
14 | /* Not present */ | |
15 | ||
16 | is bogus. If a PTE is set to PAGE_NONE then the pgprot_val is not zero and | |
17 | the entry is decoded in bogus ways, e.g. as RX GLB. That is confusing when | |
18 | analyzing mapping correctness. Check for the present bit to make an | |
19 | informed decision. | |
20 | ||
21 | Signed-off-by: Thomas Gleixner <tglx@linutronix.de> | |
22 | Cc: Andy Lutomirski <luto@kernel.org> | |
23 | Cc: Borislav Petkov <bp@alien8.de> | |
24 | Cc: Dave Hansen <dave.hansen@linux.intel.com> | |
25 | Cc: H. Peter Anvin <hpa@zytor.com> | |
26 | Cc: Josh Poimboeuf <jpoimboe@redhat.com> | |
27 | Cc: Juergen Gross <jgross@suse.com> | |
28 | Cc: Linus Torvalds <torvalds@linux-foundation.org> | |
29 | Cc: Peter Zijlstra <peterz@infradead.org> | |
30 | Cc: linux-kernel@vger.kernel.org | |
31 | Signed-off-by: Ingo Molnar <mingo@kernel.org> | |
32 | (cherry picked from commit c05344947b37f7cda726e802457370bc6eac4d26) | |
33 | Signed-off-by: Andy Whitcroft <apw@canonical.com> | |
34 | Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com> | |
35 | (cherry picked from commit d902780eaea12f23b50be4ff00f8df6157c30e4a) | |
36 | Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com> | |
37 | --- | |
38 | arch/x86/mm/dump_pagetables.c | 2 +- | |
39 | 1 file changed, 1 insertion(+), 1 deletion(-) | |
40 | ||
41 | diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c | |
42 | index 0470826d2bdc..91aa41c5e0dd 100644 | |
43 | --- a/arch/x86/mm/dump_pagetables.c | |
44 | +++ b/arch/x86/mm/dump_pagetables.c | |
45 | @@ -140,7 +140,7 @@ static void printk_prot(struct seq_file *m, pgprot_t prot, int level, bool dmsg) | |
46 | static const char * const level_name[] = | |
47 | { "cr3", "pgd", "pud", "pmd", "pte" }; | |
48 | ||
49 | - if (!pgprot_val(prot)) { | |
50 | + if (!(pr & _PAGE_PRESENT)) { | |
51 | /* Not present */ | |
52 | pt_dump_cont_printf(m, dmsg, " "); | |
53 | } else { | |
54 | -- | |
55 | 2.14.2 | |
56 |