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 <mhira...@kernel.org>
Signed-off-by: Zhou Chengming <zhouchengmi...@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
