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Backport fix for CVE-2016-0728 (local root exploit)

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We're too close to the release of Gluon 2016.1 to do a full update of our
OpenWrt tree, therefore just make a backport of this.
This commit is contained in:
Matthias Schiffer 2016-02-06 07:39:51 +01:00
parent e0e96b7b28
commit 10f7a88ba9
1 changed files with 87 additions and 0 deletions
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patches/openwrt/0048-kernel-fix-keyring-reference-leak-CVE-2016-0728.patch Normal file
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@ -0,0 +1,87 @@
From: Matthias Schiffer <mschiffer@universe-factory.net>
Date: Sat, 6 Feb 2016 07:35:33 +0100
Subject: kernel: fix keyring reference leak (CVE-2016-0728)
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
diff --git a/target/linux/generic/patches-3.18/010-KEYS-Fix-keyring-ref-leak-in-join_session_keyring.patch b/target/linux/generic/patches-3.18/010-KEYS-Fix-keyring-ref-leak-in-join_session_keyring.patch
new file mode 100644
index 0000000..9c6a969
--- /dev/null
+++ b/target/linux/generic/patches-3.18/010-KEYS-Fix-keyring-ref-leak-in-join_session_keyring.patch
@@ -0,0 +1,75 @@
+From 7ca88764d45c209791e8813131c1457c2e9e51e7 Mon Sep 17 00:00:00 2001
+From: Yevgeny Pats <yevgeny@perception-point.io>
+Date: Mon, 11 Jan 2016 12:05:28 +0000
+Subject: KEYS: Fix keyring ref leak in join_session_keyring()
+
+If a thread is asked to join as a session keyring the keyring that's already
+set as its session, we leak a keyring reference.
+
+This can be tested with the following program:
+
+ #include <stddef.h>
+ #include <stdio.h>
+ #include <sys/types.h>
+ #include <keyutils.h>
+
+ int main(int argc, const char *argv[])
+ {
+ int i = 0;
+ key_serial_t serial;
+
+ serial = keyctl(KEYCTL_JOIN_SESSION_KEYRING,
+ "leaked-keyring");
+ if (serial < 0) {
+ perror("keyctl");
+ return -1;
+ }
+
+ if (keyctl(KEYCTL_SETPERM, serial,
+ KEY_POS_ALL | KEY_USR_ALL) < 0) {
+ perror("keyctl");
+ return -1;
+ }
+
+ for (i = 0; i < 100; i++) {
+ serial = keyctl(KEYCTL_JOIN_SESSION_KEYRING,
+ "leaked-keyring");
+ if (serial < 0) {
+ perror("keyctl");
+ return -1;
+ }
+ }
+
+ return 0;
+ }
+
+If, after the program has run, there something like the following line in
+/proc/keys:
+
+3f3d898f I--Q--- 100 perm 3f3f0000 0 0 keyring leaked-keyring: empty
+
+with a usage count of 100 * the number of times the program has been run,
+then the kernel is malfunctioning. If leaked-keyring has zero usages or
+has been garbage collected, then the problem is fixed.
+
+Reported-by: Yevgeny Pats <yevgeny@perception-point.io>
+Signed-off-by: David Howells <dhowells@redhat.com>
+---
+ security/keys/process_keys.c | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
+index a3f85d2..e6d50172 100644
+--- a/security/keys/process_keys.c
++++ b/security/keys/process_keys.c
+@@ -794,6 +794,7 @@ long join_session_keyring(const char *name)
+ ret = PTR_ERR(keyring);
+ goto error2;
+ } else if (keyring == new->session_keyring) {
++ key_put(keyring);
+ ret = 0;
+ goto error2;
+ }
+--
+2.7.0.rc3
+