ipc: convert ipc_namespace.count from atomic_t to refcount_t
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/1499417992-3238-2-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>
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@ -7,6 +7,7 @@
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#include <linux/notifier.h>
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#include <linux/nsproxy.h>
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#include <linux/ns_common.h>
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#include <linux/refcount.h>
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struct user_namespace;
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@ -19,7 +20,7 @@ struct ipc_ids {
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};
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struct ipc_namespace {
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atomic_t count;
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refcount_t count;
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struct ipc_ids ids[3];
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int sem_ctls[4];
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@ -118,7 +119,7 @@ extern struct ipc_namespace *copy_ipcs(unsigned long flags,
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static inline struct ipc_namespace *get_ipc_ns(struct ipc_namespace *ns)
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{
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if (ns)
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atomic_inc(&ns->count);
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refcount_inc(&ns->count);
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return ns;
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}
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@ -29,7 +29,7 @@ DEFINE_SPINLOCK(mq_lock);
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* and not CONFIG_IPC_NS.
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*/
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struct ipc_namespace init_ipc_ns = {
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.count = ATOMIC_INIT(1),
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.count = REFCOUNT_INIT(1),
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.user_ns = &init_user_ns,
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.ns.inum = PROC_IPC_INIT_INO,
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#ifdef CONFIG_IPC_NS
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@ -50,7 +50,7 @@ static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
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goto fail_free;
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ns->ns.ops = &ipcns_operations;
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atomic_set(&ns->count, 1);
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refcount_set(&ns->count, 1);
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ns->user_ns = get_user_ns(user_ns);
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ns->ucounts = ucounts;
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@ -144,7 +144,7 @@ static void free_ipc_ns(struct ipc_namespace *ns)
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*/
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void put_ipc_ns(struct ipc_namespace *ns)
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{
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if (atomic_dec_and_lock(&ns->count, &mq_lock)) {
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if (refcount_dec_and_lock(&ns->count, &mq_lock)) {
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mq_clear_sbinfo(ns);
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spin_unlock(&mq_lock);
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mq_put_mnt(ns);
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