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author | Masami Hiramatsu <mhiramat@redhat.com> | 2008-11-12 13:26:51 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-11-12 17:17:16 -0800 |
commit | a189d0350f387786b1fb5a5d19e3a5ab0bc0cceb (patch) | |
tree | d6133d035e0d23a8271f12204e53338f8f343351 /kernel | |
parent | 3b1b3f6e57064aa8f91c290fe51cda4c74642902 (diff) | |
download | op-kernel-dev-a189d0350f387786b1fb5a5d19e3a5ab0bc0cceb.zip op-kernel-dev-a189d0350f387786b1fb5a5d19e3a5ab0bc0cceb.tar.gz |
kprobes: disable preempt for module_text_address() and kernel_text_address()
__register_kprobe() can be preempted after checking probing address but
before module_text_address() or try_module_get(), and in this interval
the module can be unloaded. In that case, try_module_get(probed_mod)
will access to invalid address, or kprobe will probe invalid address.
This patch uses preempt_disable() to protect it and uses
__module_text_address() and __kernel_text_address().
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/kprobes.c | 21 |
1 files changed, 16 insertions, 5 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 8b57a25..f83c5e4 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -613,30 +613,37 @@ static int __kprobes __register_kprobe(struct kprobe *p, return -EINVAL; p->addr = addr; - if (!kernel_text_address((unsigned long) p->addr) || - in_kprobes_functions((unsigned long) p->addr)) + preempt_disable(); + if (!__kernel_text_address((unsigned long) p->addr) || + in_kprobes_functions((unsigned long) p->addr)) { + preempt_enable(); return -EINVAL; + } p->mod_refcounted = 0; /* * Check if are we probing a module. */ - probed_mod = module_text_address((unsigned long) p->addr); + probed_mod = __module_text_address((unsigned long) p->addr); if (probed_mod) { - struct module *calling_mod = module_text_address(called_from); + struct module *calling_mod; + calling_mod = __module_text_address(called_from); /* * We must allow modules to probe themself and in this case * avoid incrementing the module refcount, so as to allow * unloading of self probing modules. */ if (calling_mod && calling_mod != probed_mod) { - if (unlikely(!try_module_get(probed_mod))) + if (unlikely(!try_module_get(probed_mod))) { + preempt_enable(); return -EINVAL; + } p->mod_refcounted = 1; } else probed_mod = NULL; } + preempt_enable(); p->nmissed = 0; INIT_LIST_HEAD(&p->list); @@ -718,6 +725,10 @@ static void __kprobes __unregister_kprobe_bottom(struct kprobe *p) struct kprobe *old_p; if (p->mod_refcounted) { + /* + * Since we've already incremented refcount, + * we don't need to disable preemption. + */ mod = module_text_address((unsigned long)p->addr); if (mod) module_put(mod); |