Messages in this thread Patch in this message | | | From | Kamal Mostafa <> | Subject | [PATCH 3.19.y-ckt 47/47] KEYS: Fix keyring ref leak in join_session_keyring() | Date | Tue, 9 Feb 2016 14:45:01 -0800 |
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3.19.8-ckt15 -stable review patch. If anyone has any objections, please let me know.
---8<------------------------------------------------------------
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: Kamal Mostafa <kamal@canonical.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 bd536cb..db91639 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; } -- 1.9.1
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