UPSTREAM: KEYS: Fix keyring ref leak in join_session_keyring()
(cherry pick from commit 23567fd052a9abb6d67fe8e7a9ccdd9800a540f2) 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> Change-Id: Ic3db0461d08011e432bf3a6a784dd62b764558e3 Git-commit: ba8bb5774ca7b1acc314c98638cf678ce0beb19a Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git Signed-off-by: Biswajit Paul <biswajitpaul@codeaurora.org>
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@ -792,6 +792,7 @@ long join_session_keyring(const char *name)
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ret = PTR_ERR(keyring);
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goto error2;
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} else if (keyring == new->session_keyring) {
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key_put(keyring);
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ret = 0;
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goto error2;
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}
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