ipc: convert kern_ipc_perm.refcount from atomic_t to refcount_t (9405c03e) · Commits · 戴 / test

refcount_t type and corresponding API should be used instead of atomic_t when the variable is used as a reference counter. This allows to avoid accidental refcounter overflows that might lead to use-after-free situations. Link: http://lkml.kernel.org/r/1499417992-3238-4-git-send-email-elena.reshetova@intel.com Signed-off-by:

Elena Reshetova <elena.reshetova@intel.com> Signed-off-by:

Hans Liljestrand <ishkamiel@gmail.com> Signed-off-by:

Kees Cook <keescook@chromium.org> Signed-off-by:

David Windsor <dwindsor@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Serge Hallyn <serge@hallyn.com> Cc: <arozansk@redhat.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

include/linux/ipc.h

+2 −1

Original line number	Diff line number	Diff line
		@@ -4,6 +4,7 @@
		#include <linux/spinlock.h>
		#include <linux/uidgid.h>
		#include <uapi/linux/ipc.h>
		#include <linux/refcount.h>

		#define IPCMNI 32768 /* <= MAX_INT limit for ipc arrays (including sysctl changes) */

		@@ -22,7 +23,7 @@ struct kern_ipc_perm {
		void *security;

		struct rcu_head rcu;
		atomic_t refcount;
		refcount_t refcount;
		} ____cacheline_aligned_in_smp __randomize_layout;

		#endif /* _LINUX_IPC_H */

ipc/util.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -232,7 +232,7 @@ int ipc_addid(struct ipc_ids ids, struct kern_ipc_perm new, int size)

		idr_preload(GFP_KERNEL);

		atomic_set(&new->refcount, 1);
		refcount_set(&new->refcount, 1);
		spin_lock_init(&new->lock);
		new->deleted = false;
		rcu_read_lock();
		@@ -397,13 +397,13 @@ void ipc_rmid(struct ipc_ids ids, struct kern_ipc_perm ipcp)

		int ipc_rcu_getref(struct kern_ipc_perm *ptr)
		{
		return atomic_inc_not_zero(&ptr->refcount);
		return refcount_inc_not_zero(&ptr->refcount);
		}

		void ipc_rcu_putref(struct kern_ipc_perm *ptr,
		void (func)(struct rcu_head head))
		{
		if (!atomic_dec_and_test(&ptr->refcount))
		if (!refcount_dec_and_test(&ptr->refcount))
		return;

		call_rcu(&ptr->rcu, func);

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