Unverified Commit 57b39aab authored by Christian Brauner's avatar Christian Brauner
Browse files

ns: add asserts for active refcount underflow 

Add a few more assert to detect active reference count underflows.

Link: https://patch.msgid.link/20251109-namespace-6-19-fixes-v1-6-ae8a4ad5a3b3@kernel.org


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent f8d5a897

include/linux/ns_common.h

+0 −1
Original line number Diff line number Diff line
@@ -294,7 +294,6 @@ void __ns_ref_active_put(struct ns_common *ns); 


static __always_inline struct ns_common *__must_check ns_get_unless_inactive(struct ns_common *ns)

{

	VFS_WARN_ON_ONCE(__ns_ref_active_read(ns) && !__ns_ref_read(ns));

	if (!__ns_ref_active_read(ns)) {

		VFS_WARN_ON_ONCE(is_ns_init_id(ns));

		return NULL;

kernel/nscommon.c

+14 −4
Original line number Diff line number Diff line
@@ -170,8 +170,10 @@ void __ns_ref_active_put(struct ns_common *ns) 
	if (is_ns_init_id(ns))

		return;



	if (!atomic_dec_and_test(&ns->__ns_ref_active))

	if (!atomic_dec_and_test(&ns->__ns_ref_active)) {

		VFS_WARN_ON_ONCE(__ns_ref_active_read(ns) < 0);

		return;

	}



	VFS_WARN_ON_ONCE(is_ns_init_id(ns));

	VFS_WARN_ON_ONCE(!__ns_ref_read(ns));
@@ -181,10 +183,12 @@ void __ns_ref_active_put(struct ns_common *ns) 
		if (!ns)

			return;

		VFS_WARN_ON_ONCE(is_ns_init_id(ns));

		if (!atomic_dec_and_test(&ns->__ns_ref_active))

		if (!atomic_dec_and_test(&ns->__ns_ref_active)) {

			VFS_WARN_ON_ONCE(__ns_ref_active_read(ns) < 0);

			return;

		}

	}

}



/*

 * The active reference count works by having each namespace that gets
@@ -280,12 +284,16 @@ void __ns_ref_active_put(struct ns_common *ns) 
 */

void __ns_ref_active_get(struct ns_common *ns)

{

	int prev;



	/* Initial namespaces are always active. */

	if (is_ns_init_id(ns))

		return;



	/* If we didn't resurrect the namespace we're done. */

	if (atomic_fetch_add(1, &ns->__ns_ref_active))

	prev = atomic_fetch_add(1, &ns->__ns_ref_active);

	VFS_WARN_ON_ONCE(prev < 0);

	if (likely(prev))

		return;



	/*
@@ -298,7 +306,9 @@ void __ns_ref_active_get(struct ns_common *ns) 
			return;



		VFS_WARN_ON_ONCE(is_ns_init_id(ns));

		if (atomic_fetch_add(1, &ns->__ns_ref_active))

		prev = atomic_fetch_add(1, &ns->__ns_ref_active);

		VFS_WARN_ON_ONCE(prev < 0);

		if (likely(prev))

			return;

	}

}