On 2017/10/26 22:39, Masami Hiramatsu wrote:
On Thu, 26 Oct 2017 20:11:25 +0800
Zhou Chengming<[email protected]> wrote:
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.
Still no good, see below comment.
Signed-off-by: Zhou Chengming<[email protected]>
---
kernel/kprobes.c | 23 ++++++-----------------
1 file changed, 6 insertions(+), 17 deletions(-)
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index a1606a4..2a4873a 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;
@@ -1536,10 +1523,6 @@ int register_kprobe(struct kprobe *p)
return PTR_ERR(addr);
p->addr = addr;
- ret = check_kprobe_rereg(p);
- if (ret)
- return ret;
-
/* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
p->flags&= KPROBE_FLAG_DISABLED;
p->nmissed = 0;
here, we already modifies the kprobe. We need to check and reject before
modifying it.
Thank you,
Ah, right. We should put the modifies after the re-reg check. I will send a
patch-v2.
Thank you.
@@ -1551,6 +1534,12 @@ int register_kprobe(struct kprobe *p)
mutex_lock(&kprobe_mutex);
+ /* Return error if the kprobe is being re-registered */
+ if (__get_valid_kprobe(p)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
old_p = get_kprobe(p->addr);
if (old_p) {
/* Since this may unoptimize old_p, locking text_mutex. */
--
1.8.3.1
