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Commit dae3c5a0 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
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[PATCH] sys_unshare: remove a broken CLONE_SIGHAND code 



sys_unshare(CLONE_SIGHAND) is broken, the code under 'if (new_sigh)' is
never executed but very wrong. Just remove it to avoid a confusion,
task_lock() has nothing to do with ->sighand changing.

Also, change the comment in unshare_sighand(). Yes, CLONE_THREAD implies
CLONE_SIGHAND, but still it looks confusing. Also, we don't need to check
current->sighand != NULL.

Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Acked-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent ae424ae4

kernel/fork.c

+4 −12
Original line number Diff line number Diff line
@@ -1544,15 +1544,13 @@ static int unshare_namespace(unsigned long unshare_flags, struct namespace **new 
}



/*

 * Unsharing of sighand for tasks created with CLONE_SIGHAND is not

 * supported yet

 * Unsharing of sighand is not supported yet

 */

static int unshare_sighand(unsigned long unshare_flags, struct sighand_struct **new_sighp)

{

	struct sighand_struct *sigh = current->sighand;



	if ((unshare_flags & CLONE_SIGHAND) &&

	    (sigh && atomic_read(&sigh->count) > 1))

	if ((unshare_flags & CLONE_SIGHAND) && atomic_read(&sigh->count) > 1)

		return -EINVAL;

	else

		return 0;
@@ -1626,7 +1624,7 @@ asmlinkage long sys_unshare(unsigned long unshare_flags) 
	int err = 0;

	struct fs_struct *fs, *new_fs = NULL;

	struct namespace *ns, *new_ns = NULL;

	struct sighand_struct *sigh, *new_sigh = NULL;

	struct sighand_struct *new_sigh = NULL;

	struct mm_struct *mm, *new_mm = NULL, *active_mm = NULL;

	struct files_struct *fd, *new_fd = NULL;

	struct sem_undo_list *new_ulist = NULL;
@@ -1671,7 +1669,7 @@ asmlinkage long sys_unshare(unsigned long unshare_flags) 
		}

	}



	if (new_fs || new_ns || new_sigh || new_mm || new_fd || new_ulist ||

	if (new_fs || new_ns || new_mm || new_fd || new_ulist ||

				new_uts || new_ipc) {



		task_lock(current);
@@ -1693,12 +1691,6 @@ asmlinkage long sys_unshare(unsigned long unshare_flags) 
			new_ns = ns;

		}



		if (new_sigh) {

			sigh = current->sighand;

			rcu_assign_pointer(current->sighand, new_sigh);

			new_sigh = sigh;

		}



		if (new_mm) {

			mm = current->mm;

			active_mm = current->active_mm;