UPSTREAM: KEYS: Fix keyring ref leak in join_session_keyring()
authorYevgeny Pats <yevgeny@perception-point.io>
Tue, 19 Jan 2016 22:09:04 +0000 (22:09 +0000)
committermobile promotions <svcmobile_promotions@nvidia.com>
Thu, 21 Jan 2016 20:32:55 +0000 (12:32 -0800)
commit07be7f19b4c356ce94642d0c2cecb93179a9a9bc
tree6213e1a67ceea4072acf48a336c5362280052150
parentfec1e971b6307c46a443934f51b3e98627ba5cf1
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.

Bug 1720836

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: I10177a58a7b3178eda95017557edaa7298594d06
(cherry picked from commit 9fc5f368bb89b65b591c4f800dfbcc7432e49de5)
Signed-off-by: Sumit Singh <sumsingh@nvidia.com>
Reviewed-on: http://git-master/r/935565
GVS: Gerrit_Virtual_Submit
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>
security/keys/process_keys.c