| From 23567fd052a9abb6d67fe8e7a9ccdd9800a540f2 Mon Sep 17 00:00:00 2001 |
| From: Yevgeny Pats <yevgeny@perception-point.io> |
| Date: Tue, 19 Jan 2016 22:09:04 +0000 |
| Subject: KEYS: Fix keyring ref leak in join_session_keyring() |
| |
| From: Yevgeny Pats <yevgeny@perception-point.io> |
| |
| 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> |
| |
| --- |
| security/keys/process_keys.c | 1 + |
| 1 file changed, 1 insertion(+) |
| |
| --- a/security/keys/process_keys.c |
| +++ b/security/keys/process_keys.c |
| @@ -792,6 +792,7 @@ long join_session_keyring(const char *na |
| ret = PTR_ERR(keyring); |
| goto error2; |
| } else if (keyring == new->session_keyring) { |
| + key_put(keyring); |
| ret = 0; |
| goto error2; |
| } |