2022-08-26 07:33:56

by Yang Yingliang

Subject: [PATCH -next 1/3] fail_function: Switch to memdup_user_nul() helper

Use memdup_user_nul() helper instead of open-coding to
simplify the code.

Signed-off-by: Yang Yingliang <[email protected]>
---
kernel/fail_function.c | 13 ++++---------
1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/kernel/fail_function.c b/kernel/fail_function.c
index 60dc825ecc2b..03643e33e4c3 100644
--- a/kernel/fail_function.c
+++ b/kernel/fail_function.c
@@ -247,15 +247,11 @@ static ssize_t fei_write(struct file *file, const char __user *buffer,
/* cut off if it is too long */
if (count > KSYM_NAME_LEN)
count = KSYM_NAME_LEN;
- buf = kmalloc(count + 1, GFP_KERNEL);
- if (!buf)
- return -ENOMEM;

- if (copy_from_user(buf, buffer, count)) {
- ret = -EFAULT;
- goto out_free;
- }
- buf[count] = '\0';
+ buf = memdup_user_nul(buffer, count);
+ if (IS_ERR(buf))
+ return PTR_ERR(buf);
+
sym = strstrip(buf);

mutex_lock(&fei_lock);
@@ -308,7 +304,6 @@ static ssize_t fei_write(struct file *file, const char __user *buffer,
}
out:
mutex_unlock(&fei_lock);
-out_free:
kfree(buf);
return ret;
}
--
2.25.1

2022-08-26 08:03:53

by Yang Yingliang

Subject: [PATCH -next 2/3] fail_function: refctor code of checking return value of register_kprobe()

Refactor the error handling of register_kprobe() to improve readability.
No functional change.

Signed-off-by: Yang Yingliang <[email protected]>
---
kernel/fail_function.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/kernel/fail_function.c b/kernel/fail_function.c
index 03643e33e4c3..893e8f9a9118 100644
--- a/kernel/fail_function.c
+++ b/kernel/fail_function.c
@@ -294,14 +294,13 @@ static ssize_t fei_write(struct file *file, const char __user *buffer,
}

ret = register_kprobe(&attr->kp);
- if (!ret)
- fei_debugfs_add_attr(attr);
- if (ret < 0)
+ if (ret) {
fei_attr_remove(attr);
- else {
- list_add_tail(&attr->list, &fei_attr_list);
- ret = count;
+ goto out;
}
+ fei_debugfs_add_attr(attr);
+ list_add_tail(&attr->list, &fei_attr_list);
+ ret = count;
out:
mutex_unlock(&fei_lock);
kfree(buf);
--
2.25.1

2022-08-26 08:16:44

by Yang Yingliang

Subject: [PATCH -next 3/3] fail_function: fix wrong use of fei_attr_remove()

If register_kprobe() fails, the new attr is not added to the list yet,
so it should call fei_attr_free() intstead.

Fixes: 4b1a29a7f542 ("error-injection: Support fault injection framework")
Signed-off-by: Yang Yingliang <[email protected]>
---
kernel/fail_function.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/fail_function.c b/kernel/fail_function.c
index 893e8f9a9118..a7ccd2930c5f 100644
--- a/kernel/fail_function.c
+++ b/kernel/fail_function.c
@@ -295,7 +295,7 @@ static ssize_t fei_write(struct file *file, const char __user *buffer,

ret = register_kprobe(&attr->kp);
if (ret) {
- fei_attr_remove(attr);
+ fei_attr_free(attr);
goto out;
}
fei_debugfs_add_attr(attr);
--
2.25.1

2022-09-12 09:49:23

by Masami Hiramatsu

Subject: Re: [PATCH -next 2/3] fail_function: refctor code of checking return value of register_kprobe()

On Fri, 26 Aug 2022 15:33:36 +0800
Yang Yingliang <[email protected]> wrote:

> Refactor the error handling of register_kprobe() to improve readability.
> No functional change.
>
> Signed-off-by: Yang Yingliang <[email protected]>

OK, but in this case, could you fold [2/3] and [3/3], because
[3/3] can not be applied without this change.

Thank you,

> ---
> kernel/fail_function.c | 11 +++++------
> 1 file changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/kernel/fail_function.c b/kernel/fail_function.c
> index 03643e33e4c3..893e8f9a9118 100644
> --- a/kernel/fail_function.c
> +++ b/kernel/fail_function.c
> @@ -294,14 +294,13 @@ static ssize_t fei_write(struct file *file, const char __user *buffer,
> }
>
> ret = register_kprobe(&attr->kp);
> - if (!ret)
> - fei_debugfs_add_attr(attr);
> - if (ret < 0)
> + if (ret) {
> fei_attr_remove(attr);
> - else {
> - list_add_tail(&attr->list, &fei_attr_list);
> - ret = count;
> + goto out;
> }
> + fei_debugfs_add_attr(attr);
> + list_add_tail(&attr->list, &fei_attr_list);
> + ret = count;
> out:
> mutex_unlock(&fei_lock);
> kfree(buf);
> --
> 2.25.1
>


--
Masami Hiramatsu (Google) <[email protected]>

2022-09-12 09:49:25

by Masami Hiramatsu

Subject: Re: [PATCH -next 1/3] fail_function: Switch to memdup_user_nul() helper

On Fri, 26 Aug 2022 15:33:35 +0800
Yang Yingliang <[email protected]> wrote:

> Use memdup_user_nul() helper instead of open-coding to
> simplify the code.
>
> Signed-off-by: Yang Yingliang <[email protected]>

Looks good to me.

Acked-by: Masami Hiramatsu (Google) <[email protected]>

Thank you!

> ---
> kernel/fail_function.c | 13 ++++---------
> 1 file changed, 4 insertions(+), 9 deletions(-)
>
> diff --git a/kernel/fail_function.c b/kernel/fail_function.c
> index 60dc825ecc2b..03643e33e4c3 100644
> --- a/kernel/fail_function.c
> +++ b/kernel/fail_function.c
> @@ -247,15 +247,11 @@ static ssize_t fei_write(struct file *file, const char __user *buffer,
> /* cut off if it is too long */
> if (count > KSYM_NAME_LEN)
> count = KSYM_NAME_LEN;
> - buf = kmalloc(count + 1, GFP_KERNEL);
> - if (!buf)
> - return -ENOMEM;
>
> - if (copy_from_user(buf, buffer, count)) {
> - ret = -EFAULT;
> - goto out_free;
> - }
> - buf[count] = '\0';
> + buf = memdup_user_nul(buffer, count);
> + if (IS_ERR(buf))
> + return PTR_ERR(buf);
> +
> sym = strstrip(buf);
>
> mutex_lock(&fei_lock);
> @@ -308,7 +304,6 @@ static ssize_t fei_write(struct file *file, const char __user *buffer,
> }
> out:
> mutex_unlock(&fei_lock);
> -out_free:
> kfree(buf);
> return ret;
> }
> --
> 2.25.1
>


--
Masami Hiramatsu (Google) <[email protected]>