linux-kernel - [PATCH] check_unshare_flags: kill the bogus CLONE

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-next>] [day] [month] [year] [list]

Date:	Sun, 21 Mar 2010 19:48:01 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Janak Desai <janak@...ibm.com>, Roland McGrath <roland@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] check_unshare_flags: kill the bogus
	CLONE_SIGHAND/sig->count check

check_unshare_flags(CLONE_SIGHAND) adds CLONE_THREAD to *flags_ptr if the
task is multithreaded to ensure unshare_thread() will fail.

Not only this is a bit strange way to return the error, this is absolutely
meaningless. If signal->count > 1 then sighand->count must be also > 1,
and unshare_sighand() will fail anyway.

In fact, all CLONE_THREAD/SIGHAND/VM checks inside sys_unshare() do not
look right. Fortunately this code doesn't really work anyway.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---

 kernel/fork.c |    8 --------
 1 file changed, 8 deletions(-)

--- 34-rc1/kernel/fork.c~UNSHARE_DONT_USE_SIG_COUNT	2010-03-21 18:37:31.000000000 +0100
+++ 34-rc1/kernel/fork.c	2010-03-21 19:08:06.000000000 +0100
@@ -1519,14 +1519,6 @@ static void check_unshare_flags(unsigned
 		*flags_ptr |= CLONE_SIGHAND;
 
 	/*
-	 * If unsharing signal handlers and the task was created
-	 * using CLONE_THREAD, then must unshare the thread
-	 */
-	if ((*flags_ptr & CLONE_SIGHAND) &&
-	    (atomic_read(&current->signal->count) > 1))
-		*flags_ptr |= CLONE_THREAD;
-
-	/*
 	 * If unsharing namespace, must also unshare filesystem information.
 	 */
 	if (*flags_ptr & CLONE_NEWNS)

--
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/