linux-kernel - [PATCH 1/1] cred: copy_process() should clear child->replacement_session

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 9 Apr 2012 21:03:50 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	David Howells <dhowells@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: [PATCH 1/1] cred: copy_process() should clear
	child->replacement_session_keyring

keyctl_session_to_parent(task) sets ->replacement_session_keyring,
it should be processed and cleared by key_replace_session_keyring().

However, this task can fork before it notices TIF_NOTIFY_RESUME and
the new child gets the bogus ->replacement_session_keyring copied by
dup_task_struct(). This is obviously wrong and, if nothing else, this
leads to put_cred(already_freed_cred).

change copy_creds() to clear this member. If copy_process() fails
before this point the wrong ->replacement_session_keyring doesn't
matter, exit_creds() won't be called.

Cc: <stable@...r.kernel.org>
Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 kernel/cred.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/kernel/cred.c b/kernel/cred.c
index 97b36ee..e70683d 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -386,6 +386,8 @@ int copy_creds(struct task_struct *p, unsigned long clone_flags)
 	struct cred *new;
 	int ret;

+	p->replacement_session_keyring = NULL;
+
 	if (
 #ifdef CONFIG_KEYS
 		!p->cred->thread_keyring &&
-- 
1.5.5.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/