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CVE-2014-8133 x86: espfix(64) bypass via set_thread_area and CLONE_SETTLS (rhbz 1172797 1174374)

This commit is contained in:
Josh Boyer 2014-12-15 14:26:22 -05:00
parent c1706593bc
commit 32f1e15e15
2 changed files with 84 additions and 0 deletions
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7
kernel.spec
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@ -627,6 +627,9 @@ Patch26096: cfg80211-don-t-WARN-about-two-consecutive-Country-IE.patch
Patch26098: move-d_rcu-from-overlapping-d_child-to-overlapping-d.patch
Patch26099: deal-with-deadlock-in-d_walk.patch
#CVE-2014-8133 rhbz 1172797 1174374
Patch26100: x86-tls-Validate-TLS-entries-to-protect-espfix.patch
# git clone ssh://git.fedorahosted.org/git/kernel-arm64.git, git diff master...devel
Patch30000: kernel-arm64.patch
@ -1363,6 +1366,9 @@ ApplyPatch cfg80211-don-t-WARN-about-two-consecutive-Country-IE.patch
ApplyPatch move-d_rcu-from-overlapping-d_child-to-overlapping-d.patch
ApplyPatch deal-with-deadlock-in-d_walk.patch
#CVE-2014-8133 rhbz 1172797 1174374
ApplyPatch x86-tls-Validate-TLS-entries-to-protect-espfix.patch
%if 0%{?aarch64patches}
ApplyPatch kernel-arm64.patch
%ifnarch aarch64 # this is stupid, but i want to notice before secondary koji does.
@ -2232,6 +2238,7 @@ fi
# || ||
%changelog
* Mon Dec 15 2014 Josh Boyer <jwboyer@fedoraproject.org>
- CVE-2014-8133 x86: espfix(64) bypass via set_thread_area and CLONE_SETTLS (rhbz 1172797 1174374)
- CVE-2014-8559 deadlock due to incorrect usage of rename_lock (rhbz 1159313 1173814)
* Fri Dec 12 2014 Kyle McMartin <kyle@fedoraproject.org>

77
x86-tls-Validate-TLS-entries-to-protect-espfix.patch Normal file
View File

@ -0,0 +1,77 @@
From: Andy Lutomirski <luto@amacapital.net>
Date: Thu, 4 Dec 2014 16:48:16 -0800
Subject: [PATCH] x86/tls: Validate TLS entries to protect espfix
Installing a 16-bit RW data segment into the GDT defeats espfix.
AFAICT this will not affect glibc, Wine, or dosemu at all.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Cc: stable@vger.kernel.org
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: security@kernel.org <security@kernel.org>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/tls.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/arch/x86/kernel/tls.c b/arch/x86/kernel/tls.c
index f7fec09e3e3a..e7650bd71109 100644
--- a/arch/x86/kernel/tls.c
+++ b/arch/x86/kernel/tls.c
@@ -27,6 +27,21 @@ static int get_free_idx(void)
return -ESRCH;
}
+static bool tls_desc_okay(const struct user_desc *info)
+{
+ if (LDT_empty(info))
+ return true;
+
+ /*
+ * espfix is required for 16-bit data segments, but espfix
+ * only works for LDT segments.
+ */
+ if (!info->seg_32bit)
+ return false;
+
+ return true;
+}
+
static void set_tls_desc(struct task_struct *p, int idx,
const struct user_desc *info, int n)
{
@@ -66,6 +81,9 @@ int do_set_thread_area(struct task_struct *p, int idx,
if (copy_from_user(&info, u_info, sizeof(info)))
return -EFAULT;
+ if (!tls_desc_okay(&info))
+ return -EINVAL;
+
if (idx == -1)
idx = info.entry_number;
@@ -192,6 +210,7 @@ int regset_tls_set(struct task_struct *target, const struct user_regset *regset,
{
struct user_desc infobuf[GDT_ENTRY_TLS_ENTRIES];
const struct user_desc *info;
+ int i;
if (pos >= GDT_ENTRY_TLS_ENTRIES * sizeof(struct user_desc) ||
(pos % sizeof(struct user_desc)) != 0 ||
@@ -205,6 +224,10 @@ int regset_tls_set(struct task_struct *target, const struct user_regset *regset,
else
info = infobuf;
+ for (i = 0; i < count / sizeof(struct user_desc); i++)
+ if (!tls_desc_okay(info + i))
+ return -EINVAL;
+
set_tls_desc(target,
GDT_ENTRY_TLS_MIN + (pos / sizeof(struct user_desc)),
info, count / sizeof(struct user_desc));
--
2.1.0