* [PATCH v2] kprobes: avoid the kprobe being re-registered
@ 2017-10-27 1:56 Zhou Chengming
2017-10-27 5:57 ` Masami Hiramatsu
0 siblings, 1 reply; 3+ messages in thread
From: Zhou Chengming @ 2017-10-27 1:56 UTC (permalink / raw)
To: mhiramat, ananth, anil.s.keshavamurthy, davem
Cc: linux-kernel, zhouchengming1
Changes from v1:
- We should put the modifies of the kprobe after the re-reg check.
- And then the address_safe check.
- When check_kprobe_address_safe() return fail, the *probed_mod
should be set to NULL, and no module refcount held.
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.
Signed-off-by: Zhou Chengming <zhouchengming1@huawei.com>
---
kernel/kprobes.c | 28 +++++++++-------------------
1 file changed, 9 insertions(+), 19 deletions(-)
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index a1606a4..f622639 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;
@@ -1501,6 +1488,7 @@ static int check_kprobe_address_safe(struct kprobe *p,
* its code to prohibit unexpected unloading.
*/
if (unlikely(!try_module_get(*probed_mod))) {
+ *probed_mod = NULL;
ret = -ENOENT;
goto out;
}
@@ -1536,9 +1524,13 @@ 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 +1539,7 @@ 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
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v2] kprobes: avoid the kprobe being re-registered
2017-10-27 1:56 [PATCH v2] kprobes: avoid the kprobe being re-registered Zhou Chengming
@ 2017-10-27 5:57 ` Masami Hiramatsu
2017-10-27 6:16 ` zhouchengming
0 siblings, 1 reply; 3+ messages in thread
From: Masami Hiramatsu @ 2017-10-27 5:57 UTC (permalink / raw)
To: Zhou Chengming; +Cc: ananth, anil.s.keshavamurthy, davem, linux-kernel
On Fri, 27 Oct 2017 09:56:40 +0800
Zhou Chengming <zhouchengming1@huawei.com> wrote:
> Changes from v1:
> - We should put the modifies of the kprobe after the re-reg check.
> - And then the address_safe check.
> - When check_kprobe_address_safe() return fail, the *probed_mod
> should be set to NULL, and no module refcount held.
Could you split this item from this patch (with initializing probe_mod = NULL),
since it is another bug?
Thank you,
>
> 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.
>
> Signed-off-by: Zhou Chengming <zhouchengming1@huawei.com>
> ---
> kernel/kprobes.c | 28 +++++++++-------------------
> 1 file changed, 9 insertions(+), 19 deletions(-)
>
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index a1606a4..f622639 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;
> @@ -1501,6 +1488,7 @@ static int check_kprobe_address_safe(struct kprobe *p,
> * its code to prohibit unexpected unloading.
> */
> if (unlikely(!try_module_get(*probed_mod))) {
> + *probed_mod = NULL;
> ret = -ENOENT;
> goto out;
> }
> @@ -1536,9 +1524,13 @@ 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 +1539,7 @@ 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
>
--
Masami Hiramatsu <mhiramat@kernel.org>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v2] kprobes: avoid the kprobe being re-registered
2017-10-27 5:57 ` Masami Hiramatsu
@ 2017-10-27 6:16 ` zhouchengming
0 siblings, 0 replies; 3+ messages in thread
From: zhouchengming @ 2017-10-27 6:16 UTC (permalink / raw)
To: Masami Hiramatsu; +Cc: ananth, anil.s.keshavamurthy, davem, linux-kernel
On 2017/10/27 13:57, Masami Hiramatsu wrote:
> On Fri, 27 Oct 2017 09:56:40 +0800
> Zhou Chengming<zhouchengming1@huawei.com> wrote:
>
>> Changes from v1:
>> - We should put the modifies of the kprobe after the re-reg check.
>> - And then the address_safe check.
>> - When check_kprobe_address_safe() return fail, the *probed_mod
>> should be set to NULL, and no module refcount held.
> Could you split this item from this patch (with initializing probe_mod = NULL),
> since it is another bug?
>
> Thank you,
Ok, it seems more reasonable. I will split this patch into two patches later.
Thank you.
>> 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.
>>
>> Signed-off-by: Zhou Chengming<zhouchengming1@huawei.com>
>> ---
>> kernel/kprobes.c | 28 +++++++++-------------------
>> 1 file changed, 9 insertions(+), 19 deletions(-)
>>
>> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
>> index a1606a4..f622639 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;
>> @@ -1501,6 +1488,7 @@ static int check_kprobe_address_safe(struct kprobe *p,
>> * its code to prohibit unexpected unloading.
>> */
>> if (unlikely(!try_module_get(*probed_mod))) {
>> + *probed_mod = NULL;
>> ret = -ENOENT;
>> goto out;
>> }
>> @@ -1536,9 +1524,13 @@ 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 +1539,7 @@ 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
>>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2017-10-27 6:19 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
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2017-10-27 1:56 [PATCH v2] kprobes: avoid the kprobe being re-registered Zhou Chengming
2017-10-27 5:57 ` Masami Hiramatsu
2017-10-27 6:16 ` zhouchengming
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