[linux] 01/02: KEYS: Fix keyring ref leak in join_session_keyring() (CVE-2016-0728)

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carnil pushed a commit to branch jessie-security
in repository linux.

commit 0ac8c3e88cf1ea329ede357f2a01a9b1a8734e24
Author: Salvatore Bonaccorso <carnil at debian.org>
Date:   Fri Jan 15 20:08:53 2016 +0100

    KEYS: Fix keyring ref leak in join_session_keyring() (CVE-2016-0728)
---
 debian/changelog                                   |  1 +
 ...-keyring-ref-leak-in-join_session_keyring.patch | 75 ++++++++++++++++++++++
 debian/patches/series                              |  1 +
 3 files changed, 77 insertions(+)

diff --git a/debian/changelog b/debian/changelog
index 05025a4..e898661 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -9,6 +9,7 @@ linux (3.16.7-ckt20-1+deb8u3) UNRELEASED; urgency=medium
 
   [ Salvatore Bonaccorso ]
   * unix: properly account for FDs passed over unix sockets (CVE-2013-4312)
+  * KEYS: Fix keyring ref leak in join_session_keyring() (CVE-2016-0728)
 
  -- Ben Hutchings <ben at decadent.org.uk>  Thu, 14 Jan 2016 23:36:13 +0000
 
diff --git a/debian/patches/bugfix/all/KEYS-Fix-keyring-ref-leak-in-join_session_keyring.patch b/debian/patches/bugfix/all/KEYS-Fix-keyring-ref-leak-in-join_session_keyring.patch
new file mode 100644
index 0000000..9c6a969
--- /dev/null
+++ b/debian/patches/bugfix/all/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 at 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 at perception-point.io>
+Signed-off-by: David Howells <dhowells at 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
+
diff --git a/debian/patches/series b/debian/patches/series
index e6b9cc0..a67d069 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -675,3 +675,4 @@ bugfix/all/sctp-prevent-soft-lockup-when-sctp_accept-is-called-.patch
 bugfix/all/tty-fix-unsafe-ldisc-reference-via-ioctl-tiocgetd.patch
 bugfix/all/unix-properly-account-for-FDs-passed-over-unix-socke.patch
 debian/unix-fix-abi-change-for-cve-2013-4312-fix.patch
+bugfix/all/KEYS-Fix-keyring-ref-leak-in-join_session_keyring.patch

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