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authorYevgeny Pats <yevgeny@perception-point.io>2016-01-19 22:09:04 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-01-22 20:34:55 -0800
commit2e647bca7a2c885acdcd89da631b8dd5edc9e310 (patch)
treec09d591bcaebfdb48da39831fe8b0546ecc618a0
parent92264cc9c4636340a492d78f8f2ae3b3424e7fdd (diff)
KEYS: Fix keyring ref leak in join_session_keyring()
commit 23567fd052a9abb6d67fe8e7a9ccdd9800a540f2 upstream. This fixes CVE-2016-0728. 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> Acked-by: Don Zickus <dzickus@redhat.com> Acked-by: Prarit Bhargava <prarit@redhat.com> Acked-by: Jarod Wilson <jarod@redhat.com> Signed-off-by: James Morris <james.l.morris@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--security/keys/process_keys.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index 0cf8a130a267..4e56371f239f 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -793,6 +793,7 @@ 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;
}