2021-05-31 03:03:09

by Yang Yingliang

Subject: [PATCH -next v2] cifsd: check return value of ksmbd_vfs_getcasexattr() correctly

If ksmbd_vfs_getcasexattr() returns -ENOMEM, stream_buf is NULL,
it will cause null-ptr-deref when using it to copy memory. So we
need check the return value of ksmbd_vfs_getcasexattr() by comparing
with 0.

Fixes: f44158485826 ("cifsd: add file operations")
Signed-off-by: Yang Yingliang <[email protected]>
---
v2:
Handle the case ksmbd_vfs_getcasexattr() returns 0.
---
fs/cifsd/vfs.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/fs/cifsd/vfs.c b/fs/cifsd/vfs.c
index 97d5584ec870..2a9cc0bc7726 100644
--- a/fs/cifsd/vfs.c
+++ b/fs/cifsd/vfs.c
@@ -274,7 +274,6 @@ static int ksmbd_vfs_stream_read(struct ksmbd_file *fp, char *buf, loff_t *pos,
{
ssize_t v_len;
char *stream_buf = NULL;
- int err;

ksmbd_debug(VFS, "read stream data pos : %llu, count : %zd\n",
*pos, count);
@@ -283,10 +282,9 @@ static int ksmbd_vfs_stream_read(struct ksmbd_file *fp, char *buf, loff_t *pos,
fp->stream.name,
fp->stream.size,
&stream_buf);
- if (v_len == -ENOENT) {
+ if ((int)v_len <= 0) {
ksmbd_err("not found stream in xattr : %zd\n", v_len);
- err = -ENOENT;
- return err;
+ return v_len == 0 ? -ENOENT : (int)v_len;
}

memcpy(buf, &stream_buf[*pos], count);
@@ -415,9 +413,9 @@ static int ksmbd_vfs_stream_write(struct ksmbd_file *fp, char *buf, loff_t *pos,
fp->stream.name,
fp->stream.size,
&stream_buf);
- if (v_len == -ENOENT) {
+ if ((int)v_len <= 0) {
ksmbd_err("not found stream in xattr : %zd\n", v_len);
- err = -ENOENT;
+ err = v_len == 0 ? -ENOENT : (int)v_len;
goto out;
}

--
2.25.1

2021-05-31 05:40:34

by Hyunchul Lee

Subject: Re: [PATCH -next v2] cifsd: check return value of ksmbd_vfs_getcasexattr() correctly

2021년 5월 31일 (월) 오후 12:01, Yang Yingliang <[email protected]>님이 작성:
>
> If ksmbd_vfs_getcasexattr() returns -ENOMEM, stream_buf is NULL,
> it will cause null-ptr-deref when using it to copy memory. So we
> need check the return value of ksmbd_vfs_getcasexattr() by comparing
> with 0.
>
> Fixes: f44158485826 ("cifsd: add file operations")
> Signed-off-by: Yang Yingliang <[email protected]>
> ---
> v2:
> Handle the case ksmbd_vfs_getcasexattr() returns 0.
> ---
> fs/cifsd/vfs.c | 10 ++++------
> 1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/fs/cifsd/vfs.c b/fs/cifsd/vfs.c
> index 97d5584ec870..2a9cc0bc7726 100644
> --- a/fs/cifsd/vfs.c
> +++ b/fs/cifsd/vfs.c
> @@ -274,7 +274,6 @@ static int ksmbd_vfs_stream_read(struct ksmbd_file *fp, char *buf, loff_t *pos,
> {
> ssize_t v_len;
> char *stream_buf = NULL;
> - int err;
>
> ksmbd_debug(VFS, "read stream data pos : %llu, count : %zd\n",
> *pos, count);
> @@ -283,10 +282,9 @@ static int ksmbd_vfs_stream_read(struct ksmbd_file *fp, char *buf, loff_t *pos,
> fp->stream.name,
> fp->stream.size,
> &stream_buf);
> - if (v_len == -ENOENT) {
> + if ((int)v_len <= 0) {
> ksmbd_err("not found stream in xattr : %zd\n", v_len);
> - err = -ENOENT;
> - return err;
> + return v_len == 0 ? -ENOENT : (int)v_len;

How about making ksmbd_vfs_getcasexattr return -ENONENT instead of
returning 0 to
remove duplicate error handling code?

Thanks,
Hyunchul

> }
>
> memcpy(buf, &stream_buf[*pos], count);
> @@ -415,9 +413,9 @@ static int ksmbd_vfs_stream_write(struct ksmbd_file *fp, char *buf, loff_t *pos,
> fp->stream.name,
> fp->stream.size,
> &stream_buf);
> - if (v_len == -ENOENT) {
> + if ((int)v_len <= 0) {
> ksmbd_err("not found stream in xattr : %zd\n", v_len);
> - err = -ENOENT;
> + err = v_len == 0 ? -ENOENT : (int)v_len;
> goto out;
> }
>
> --
> 2.25.1
>

2021-05-31 06:11:57

by Yang Yingliang

Subject: Re: [PATCH -next v2] cifsd: check return value of ksmbd_vfs_getcasexattr() correctly

On 2021/5/31 13:38, Hyunchul Lee wrote:
> 2021년 5월 31일 (월) 오후 12:01, Yang Yingliang <[email protected]>님이 작성:
>> If ksmbd_vfs_getcasexattr() returns -ENOMEM, stream_buf is NULL,
>> it will cause null-ptr-deref when using it to copy memory. So we
>> need check the return value of ksmbd_vfs_getcasexattr() by comparing
>> with 0.
>>
>> Fixes: f44158485826 ("cifsd: add file operations")
>> Signed-off-by: Yang Yingliang <[email protected]>
>> ---
>> v2:
>> Handle the case ksmbd_vfs_getcasexattr() returns 0.
>> ---
>> fs/cifsd/vfs.c | 10 ++++------
>> 1 file changed, 4 insertions(+), 6 deletions(-)
>>
>> diff --git a/fs/cifsd/vfs.c b/fs/cifsd/vfs.c
>> index 97d5584ec870..2a9cc0bc7726 100644
>> --- a/fs/cifsd/vfs.c
>> +++ b/fs/cifsd/vfs.c
>> @@ -274,7 +274,6 @@ static int ksmbd_vfs_stream_read(struct ksmbd_file *fp, char *buf, loff_t *pos,
>> {
>> ssize_t v_len;
>> char *stream_buf = NULL;
>> - int err;
>>
>> ksmbd_debug(VFS, "read stream data pos : %llu, count : %zd\n",
>> *pos, count);
>> @@ -283,10 +282,9 @@ static int ksmbd_vfs_stream_read(struct ksmbd_file *fp, char *buf, loff_t *pos,
>> fp->stream.name,
>> fp->stream.size,
>> &stream_buf);
>> - if (v_len == -ENOENT) {
>> + if ((int)v_len <= 0) {
>> ksmbd_err("not found stream in xattr : %zd\n", v_len);
>> - err = -ENOENT;
>> - return err;
>> + return v_len == 0 ? -ENOENT : (int)v_len;
> How about making ksmbd_vfs_getcasexattr return -ENONENT instead of
> returning 0 to
> remove duplicate error handling code?
Yes, I think it's ok, I will send a v3 later.

Thanks,
Yang
>
> Thanks,
> Hyunchul
>
>> }
>>
>> memcpy(buf, &stream_buf[*pos], count);
>> @@ -415,9 +413,9 @@ static int ksmbd_vfs_stream_write(struct ksmbd_file *fp, char *buf, loff_t *pos,
>> fp->stream.name,
>> fp->stream.size,
>> &stream_buf);
>> - if (v_len == -ENOENT) {
>> + if ((int)v_len <= 0) {
>> ksmbd_err("not found stream in xattr : %zd\n", v_len);
>> - err = -ENOENT;
>> + err = v_len == 0 ? -ENOENT : (int)v_len;
>> goto out;
>> }
>>
>> --
>> 2.25.1
>>
> .