[PATCH] Kprobes: Reference count the modules when probed on it
When a Kprobes are inserted/removed on a modules, the modules must be ref counted so as not to allow to unload while probes are registered on that module. Without this patch, the probed module is free to unload, and when the probing module unregister the probe, the kpobes code while trying to replace the original instruction might crash. Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Mao Bibo <bibo.mao@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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1 changed files with 16 additions and 2 deletions
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@ -462,9 +462,16 @@ int __kprobes register_kprobe(struct kprobe *p)
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int ret = 0;
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int ret = 0;
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unsigned long flags = 0;
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unsigned long flags = 0;
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struct kprobe *old_p;
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struct kprobe *old_p;
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struct module *mod;
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if ((!kernel_text_address((unsigned long) p->addr)) ||
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in_kprobes_functions((unsigned long) p->addr))
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return -EINVAL;
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if ((mod = module_text_address((unsigned long) p->addr)) &&
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(unlikely(!try_module_get(mod))))
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return -EINVAL;
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if ((ret = in_kprobes_functions((unsigned long) p->addr)) != 0)
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return ret;
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if ((ret = arch_prepare_kprobe(p)) != 0)
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if ((ret = arch_prepare_kprobe(p)) != 0)
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goto rm_kprobe;
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goto rm_kprobe;
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@ -488,6 +495,8 @@ int __kprobes register_kprobe(struct kprobe *p)
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rm_kprobe:
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rm_kprobe:
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if (ret == -EEXIST)
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if (ret == -EEXIST)
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arch_remove_kprobe(p);
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arch_remove_kprobe(p);
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if (ret && mod)
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module_put(mod);
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return ret;
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return ret;
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}
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}
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@ -495,6 +504,7 @@ void __kprobes unregister_kprobe(struct kprobe *p)
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{
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{
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unsigned long flags;
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unsigned long flags;
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struct kprobe *old_p;
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struct kprobe *old_p;
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struct module *mod;
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spin_lock_irqsave(&kprobe_lock, flags);
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spin_lock_irqsave(&kprobe_lock, flags);
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old_p = get_kprobe(p->addr);
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old_p = get_kprobe(p->addr);
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@ -506,6 +516,10 @@ void __kprobes unregister_kprobe(struct kprobe *p)
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cleanup_kprobe(p, flags);
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cleanup_kprobe(p, flags);
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synchronize_sched();
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synchronize_sched();
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if ((mod = module_text_address((unsigned long)p->addr)))
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module_put(mod);
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if (old_p->pre_handler == aggr_pre_handler &&
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if (old_p->pre_handler == aggr_pre_handler &&
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list_empty(&old_p->list))
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list_empty(&old_p->list))
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kfree(old_p);
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kfree(old_p);
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