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| author | David Howells <dhowells@redhat.com> | 2010-09-10 09:59:51 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-09-10 07:30:00 -0700 |
| commit | 3d96406c7da1ed5811ea52a3b0905f4f0e295376 (patch) | |
| tree | 051e3a0ab6b0c9d9ac12b88fd244ff09766f8f50 /security | |
| parent | 9d1ac65a9698513d00e5608d93fca0c53f536c14 (diff) | |
| download | lwn-3d96406c7da1ed5811ea52a3b0905f4f0e295376.tar.gz lwn-3d96406c7da1ed5811ea52a3b0905f4f0e295376.zip | |
KEYS: Fix bug in keyctl_session_to_parent() if parent has no session keyring
Fix a bug in keyctl_session_to_parent() whereby it tries to check the ownership
of the parent process's session keyring whether or not the parent has a session
keyring [CVE-2010-2960].
This results in the following oops:
BUG: unable to handle kernel NULL pointer dereference at 00000000000000a0
IP: [<ffffffff811ae4dd>] keyctl_session_to_parent+0x251/0x443
...
Call Trace:
[<ffffffff811ae2f3>] ? keyctl_session_to_parent+0x67/0x443
[<ffffffff8109d286>] ? __do_fault+0x24b/0x3d0
[<ffffffff811af98c>] sys_keyctl+0xb4/0xb8
[<ffffffff81001eab>] system_call_fastpath+0x16/0x1b
if the parent process has no session keyring.
If the system is using pam_keyinit then it mostly protected against this as all
processes derived from a login will have inherited the session keyring created
by pam_keyinit during the log in procedure.
To test this, pam_keyinit calls need to be commented out in /etc/pam.d/.
Reported-by: Tavis Ormandy <taviso@cmpxchg8b.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Tavis Ormandy <taviso@cmpxchg8b.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'security')
| -rw-r--r-- | security/keys/keyctl.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c index 3868c6700b58..60924f6a52db 100644 --- a/security/keys/keyctl.c +++ b/security/keys/keyctl.c @@ -1305,7 +1305,8 @@ long keyctl_session_to_parent(void) goto not_permitted; /* the keyrings must have the same UID */ - if (pcred->tgcred->session_keyring->uid != mycred->euid || + if ((pcred->tgcred->session_keyring && + pcred->tgcred->session_keyring->uid != mycred->euid) || mycred->tgcred->session_keyring->uid != mycred->euid) goto not_permitted; |