2018-01-06 14:13:39 +00:00
|
|
|
From f7b3a0038fd5bdc21d05f09002e16db3ea8e6e3b Mon Sep 17 00:00:00 2001
|
|
|
|
|
From: Thomas Gleixner <tglx@linutronix.de>
|
|
|
|
|
Date: Sun, 31 Dec 2017 11:24:34 +0100
|
2018-01-08 09:25:09 +00:00
|
|
|
Subject: [PATCH 221/241] x86/ldt: Plug memory leak in error path
|
2018-01-06 14:13:39 +00:00
|
|
|
MIME-Version: 1.0
|
|
|
|
|
Content-Type: text/plain; charset=UTF-8
|
|
|
|
|
Content-Transfer-Encoding: 8bit
|
|
|
|
|
|
|
|
|
|
CVE-2017-5754
|
|
|
|
|
|
|
|
|
|
The error path in write_ldt() tries to free 'old_ldt' instead of the newly
|
|
|
|
|
allocated 'new_ldt', resulting in a memory leak. It also misses to clean up a
|
|
|
|
|
half populated LDT pagetable, which is not a leak as it gets cleaned up
|
|
|
|
|
when the process exits.
|
|
|
|
|
|
|
|
|
|
Free both the potentially half populated LDT pagetable and the newly
|
|
|
|
|
allocated LDT struct. This can be done unconditionally because once an LDT
|
|
|
|
|
is mapped subsequent maps will succeed, because the PTE page is already
|
|
|
|
|
populated and the two LDTs fit into that single page.
|
|
|
|
|
|
|
|
|
|
Reported-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
|
|
|
|
|
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
|
|
|
|
|
Cc: Andy Lutomirski <luto@kernel.org>
|
|
|
|
|
Cc: Borislav Petkov <bp@alien8.de>
|
|
|
|
|
Cc: Dave Hansen <dave.hansen@linux.intel.com>
|
|
|
|
|
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
|
|
|
|
|
Cc: Linus Torvalds <torvalds@linux-foundation.org>
|
|
|
|
|
Cc: Linus Torvalds <torvalds@linuxfoundation.org>
|
|
|
|
|
Cc: Peter Zijlstra <peterz@infradead.org>
|
|
|
|
|
Fixes: f55f0501cbf6 ("x86/pti: Put the LDT in its own PGD if PTI is on")
|
|
|
|
|
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1712311121340.1899@nanos
|
|
|
|
|
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
|
|
|
|
(cherry picked from commit a62d69857aab4caa43049e72fe0ed5c4a60518dd)
|
|
|
|
|
Signed-off-by: Andy Whitcroft <apw@canonical.com>
|
|
|
|
|
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
|
|
|
|
|
(cherry picked from commit 03d02494f6253d0bdca7254d85e50786448c14f9)
|
|
|
|
|
Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
|
|
|
|
|
---
|
|
|
|
|
arch/x86/kernel/ldt.c | 8 +++++++-
|
|
|
|
|
1 file changed, 7 insertions(+), 1 deletion(-)
|
|
|
|
|
|
|
|
|
|
diff --git a/arch/x86/kernel/ldt.c b/arch/x86/kernel/ldt.c
|
|
|
|
|
index 2260eb6e2de7..9a35b7e541bc 100644
|
|
|
|
|
--- a/arch/x86/kernel/ldt.c
|
|
|
|
|
+++ b/arch/x86/kernel/ldt.c
|
|
|
|
|
@@ -420,7 +420,13 @@ static int write_ldt(void __user *ptr, unsigned long bytecount, int oldmode)
|
|
|
|
|
*/
|
|
|
|
|
error = map_ldt_struct(mm, new_ldt, old_ldt ? !old_ldt->slot : 0);
|
|
|
|
|
if (error) {
|
|
|
|
|
- free_ldt_struct(old_ldt);
|
|
|
|
|
+ /*
|
|
|
|
|
+ * This only can fail for the first LDT setup. If an LDT is
|
|
|
|
|
+ * already installed then the PTE page is already
|
|
|
|
|
+ * populated. Mop up a half populated page table.
|
|
|
|
|
+ */
|
|
|
|
|
+ free_ldt_pgtables(mm);
|
|
|
|
|
+ free_ldt_struct(new_ldt);
|
|
|
|
|
goto out_unlock;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
--
|
|
|
|
|
2.14.2
|
|
|
|
|
|
