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* [PATCH -next v2] cifsd: check return value of ksmbd_vfs_getcasexattr() correctly
@ 2021-05-31  3:05 Yang Yingliang
  2021-05-31  5:38 ` Hyunchul Lee
  0 siblings, 1 reply; 3+ messages in thread
From: Yang Yingliang @ 2021-05-31  3:05 UTC (permalink / raw)
  To: linux-kernel, linux-cifsd-devel, linux-cifs
  Cc: namjae.jeon, sergey.senozhatsky, sfrench, hyc.lee

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 <yangyingliang@huawei.com>
---
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


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH -next v2] cifsd: check return value of ksmbd_vfs_getcasexattr() correctly
  2021-05-31  3:05 [PATCH -next v2] cifsd: check return value of ksmbd_vfs_getcasexattr() correctly Yang Yingliang
@ 2021-05-31  5:38 ` Hyunchul Lee
  2021-05-31  6:09   ` Yang Yingliang
  0 siblings, 1 reply; 3+ messages in thread
From: Hyunchul Lee @ 2021-05-31  5:38 UTC (permalink / raw)
  To: Yang Yingliang
  Cc: LKML, linux-cifsd-devel, linux-cifs, Namjae Jeon,
	Sergey Senozhatsky, Steve French

2021년 5월 31일 (월) 오후 12:01, Yang Yingliang <yangyingliang@huawei.com>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 <yangyingliang@huawei.com>
> ---
> 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
>

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH -next v2] cifsd: check return value of ksmbd_vfs_getcasexattr() correctly
  2021-05-31  5:38 ` Hyunchul Lee
@ 2021-05-31  6:09   ` Yang Yingliang
  0 siblings, 0 replies; 3+ messages in thread
From: Yang Yingliang @ 2021-05-31  6:09 UTC (permalink / raw)
  To: Hyunchul Lee
  Cc: LKML, linux-cifsd-devel, linux-cifs, Namjae Jeon,
	Sergey Senozhatsky, Steve French


On 2021/5/31 13:38, Hyunchul Lee wrote:
> 2021년 5월 31일 (월) 오후 12:01, Yang Yingliang <yangyingliang@huawei.com>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 <yangyingliang@huawei.com>
>> ---
>> 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
>>
> .

^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2021-05-31  6:09 UTC | newest]

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2021-05-31  3:05 [PATCH -next v2] cifsd: check return value of ksmbd_vfs_getcasexattr() correctly Yang Yingliang
2021-05-31  5:38 ` Hyunchul Lee
2021-05-31  6:09   ` Yang Yingliang

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