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From: Yinghai Lu <yinghai@kernel.org>
To: Matt Fleming <matt.fleming@intel.com>,
	"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
	Kees Cook <keescook@chromium.org>, Borislav Petkov <bp@suse.de>,
	Baoquan He <bhe@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Jiri Kosina <jkosina@suse.cz>,
	linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org,
	Yinghai Lu <yinghai@kernel.org>
Subject: [PATCH v3 4/7] x86, kaslr: Access the correct kaslr_enabled variable
Date: Sat,  7 Mar 2015 14:07:18 -0800	[thread overview]
Message-ID: <1425766041-6551-5-git-send-email-yinghai@kernel.org> (raw)
In-Reply-To: <1425766041-6551-1-git-send-email-yinghai@kernel.org>

Commit

  f47233c2d34f ("x86/mm/ASLR: Propagate base load address calculation")

started passing KASLR status to kernel proper, but it uses a physical
address as the vaule, leading to parsing bogus KASLR status in kernel
proper.

The setup_data linked list and thus the element which contains
kaslr_enabled is chained together using physical addresses. At the time
when we access it in the kernel proper, we're already running with
paging enabled and therefore must access it through its virtual address.

This patch changes the code to use early_memmap() and access the value.

-v3: add checking return from early_memmap according to Boris.
-v4: add description about setup_data accessing from Boris to change log.

Fixes: f47233c2d34f ("x86/mm/ASLR: Propagate base load address calculation")
Cc: Matt Fleming <matt.fleming@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
---
 arch/x86/kernel/setup.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 98dc931..912f124 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -429,7 +429,18 @@ static void __init reserve_initrd(void)
 
 static void __init parse_kaslr_setup(u64 pa_data, u32 data_len)
 {
-	kaslr_enabled = (bool)(pa_data + sizeof(struct setup_data));
+	/* kaslr_setup_data is defined in aslr.c */
+	unsigned char *data;
+	unsigned long offset = sizeof(struct setup_data);
+
+	data = early_memremap(pa_data, offset + 1);
+	if (!data) {
+		kaslr_enabled = true;
+		return;
+	}
+
+	kaslr_enabled = *(data + offset);
+	early_memunmap(data, offset + 1);
 }
 
 static void __init parse_setup_data(void)
-- 
1.8.4.5


  parent reply	other threads:[~2015-03-07 22:08 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-07 22:07 [PATCH v3 0/7] x86, boot: clean up kasl Yinghai Lu
2015-03-07 22:07 ` [PATCH v3 1/7] x86, kaslr: Use init_size instead of run_size Yinghai Lu
2015-03-09 12:49   ` Borislav Petkov
2015-03-09 15:58     ` Ingo Molnar
2015-03-09 15:58       ` Borislav Petkov
2015-03-09 19:35     ` Yinghai Lu
2015-03-09 20:00       ` Borislav Petkov
2015-03-09 20:06         ` Yinghai Lu
2015-03-09 20:18           ` Borislav Petkov
2015-03-09 21:28             ` Yinghai Lu
2015-03-10  0:42   ` Kees Cook
2015-03-13 12:27   ` Ingo Molnar
2015-03-14  2:47     ` Yinghai Lu
2015-03-14  7:53       ` Ingo Molnar
2015-03-14  9:59         ` Borislav Petkov
2015-03-16 10:06           ` [PATCH] Revert "x86/mm/ASLR: Propagate base load address calculation" Borislav Petkov
2015-03-16 12:11             ` [tip:x86/urgent] " tip-bot for Borislav Petkov
2015-03-16 19:32               ` Yinghai Lu
2015-03-16 13:56             ` [PATCH] " Jiri Kosina
2015-03-16 19:15               ` Yinghai Lu
2015-03-17  8:14                 ` Ingo Molnar
2015-03-07 22:07 ` [PATCH v3 2/7] x86, boot: Move ZO to end of buffer Yinghai Lu
2015-03-10  0:54   ` Kees Cook
2015-03-10  1:04     ` Yinghai Lu
2015-03-10  5:59     ` Borislav Petkov
2015-03-10  8:00   ` Borislav Petkov
2015-03-10  9:34     ` Jiri Kosina
2015-03-10  9:35       ` Borislav Petkov
2015-03-10 15:11     ` Yinghai Lu
2015-03-10 15:13       ` Borislav Petkov
2015-03-10 16:59     ` Kees Cook
2015-03-07 22:07 ` [PATCH v3 3/7] x86, boot: Don't overlap VO with ZO data Yinghai Lu
2015-03-10  9:34   ` Borislav Petkov
2015-03-10 15:05     ` Yinghai Lu
2015-03-10 15:10       ` Borislav Petkov
2015-03-10 15:17         ` Yinghai Lu
2015-03-10 15:21           ` Borislav Petkov
2015-03-10 15:42             ` Yinghai Lu
2015-03-10 15:48               ` Borislav Petkov
2015-03-10 19:29                 ` Yinghai Lu
2015-03-07 22:07 ` Yinghai Lu [this message]
2015-03-10  0:55   ` [PATCH v3 4/7] x86, kaslr: Access the correct kaslr_enabled variable Kees Cook
2015-03-07 22:07 ` [PATCH v3 5/7] x86, kaslr: Consolidate mem_avoid array filling Yinghai Lu
2015-03-10  1:00   ` Kees Cook
2015-03-10  1:10     ` Yinghai Lu
2015-03-10  1:26       ` Kees Cook
2015-03-07 22:07 ` [PATCH v3 6/7] x86, boot: Split kernel_ident_mapping_init to another file Yinghai Lu
2015-03-10  1:03   ` Kees Cook
2015-03-07 22:07 ` [PATCH v3 7/7] x86, kaslr, 64bit: Set new or extra ident_mapping Yinghai Lu
2015-03-10  1:09   ` Kees Cook
2015-03-10  1:14     ` Yinghai Lu
2015-03-10  6:54       ` Yinghai Lu
2015-03-10  0:39 ` [PATCH v3 0/7] x86, boot: clean up kasl Kees Cook
2015-03-10  0:54   ` Yinghai Lu

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