Messages in this thread Patch in this message | | | From | Zhou Chengming <> | Subject | [PATCH v3 1/2] kprobes: avoid the kprobe being re-registered | Date | Fri, 27 Oct 2017 17:23:14 +0800 |
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Changes: - We should put the modifies of the kprobe after the re-reg check. - And then the address_safe check.
Old code use check_kprobe_rereg() to check if the kprobe has been registered already, but check_kprobe_rereg() will release the kprobe_mutex then, so maybe two paths will pass the check and register the same kprobe. This patch put the check inside the mutex.
Suggested-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Zhou Chengming <zhouchengming1@huawei.com> --- kernel/kprobes.c | 27 ++++++++------------------- 1 file changed, 8 insertions(+), 19 deletions(-)
diff --git a/kernel/kprobes.c b/kernel/kprobes.c index a1606a4..1eeedac 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1443,19 +1443,6 @@ static struct kprobe *__get_valid_kprobe(struct kprobe *p) return ap; } -/* Return error if the kprobe is being re-registered */ -static inline int check_kprobe_rereg(struct kprobe *p) -{ - int ret = 0; - - mutex_lock(&kprobe_mutex); - if (__get_valid_kprobe(p)) - ret = -EINVAL; - mutex_unlock(&kprobe_mutex); - - return ret; -} - int __weak arch_check_ftrace_location(struct kprobe *p) { unsigned long ftrace_addr; @@ -1536,9 +1523,13 @@ int register_kprobe(struct kprobe *p) return PTR_ERR(addr); p->addr = addr; - ret = check_kprobe_rereg(p); - if (ret) - return ret; + mutex_lock(&kprobe_mutex); + + /* Return error if the kprobe is being re-registered */ + if (__get_valid_kprobe(p)) { + ret = -EINVAL; + goto out; + } /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */ p->flags &= KPROBE_FLAG_DISABLED; @@ -1547,9 +1538,7 @@ int register_kprobe(struct kprobe *p) ret = check_kprobe_address_safe(p, &probed_mod); if (ret) - return ret; - - mutex_lock(&kprobe_mutex); + goto out; old_p = get_kprobe(p->addr); if (old_p) { -- 1.8.3.1
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