2021-05-31 06:20:46

by Yang Yingliang

Subject: [PATCH -next v3] 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]>
---
v3:
Handle the 0 return value in ksmbd_vfs_getcasexattr().

v2:
Handle the case ksmbd_vfs_getcasexattr() returns 0.
---
fs/cifsd/vfs.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/fs/cifsd/vfs.c b/fs/cifsd/vfs.c
index 97d5584ec870..a56ec1f7f941 100644
--- a/fs/cifsd/vfs.c
+++ b/fs/cifsd/vfs.c
@@ -266,7 +266,7 @@ static ssize_t ksmbd_vfs_getcasexattr(struct dentry *dentry, char *attr_name,

out:
kvfree(xattr_list);
- return value_len;
+ return value_len == 0 ? -ENOENT : value_len;
}

static int ksmbd_vfs_stream_read(struct ksmbd_file *fp, char *buf, loff_t *pos,
@@ -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 (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 = (int)v_len;
goto out;
}

--
2.25.1

2021-05-31 07:51:28

by Hyunchul Lee

Subject: Re: [PATCH -next v3] cifsd: check return value of ksmbd_vfs_getcasexattr() correctly

This looks good to me.

2021년 5월 31일 (월) 오후 3:19, 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]>
> ---
> v3:
> Handle the 0 return value in ksmbd_vfs_getcasexattr().
>
> v2:
> Handle the case ksmbd_vfs_getcasexattr() returns 0.
> ---
> fs/cifsd/vfs.c | 12 +++++-------
> 1 file changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/fs/cifsd/vfs.c b/fs/cifsd/vfs.c
> index 97d5584ec870..a56ec1f7f941 100644
> --- a/fs/cifsd/vfs.c
> +++ b/fs/cifsd/vfs.c
> @@ -266,7 +266,7 @@ static ssize_t ksmbd_vfs_getcasexattr(struct dentry *dentry, char *attr_name,
>
> out:
> kvfree(xattr_list);
> - return value_len;
> + return value_len == 0 ? -ENOENT : value_len;
> }
>
> static int ksmbd_vfs_stream_read(struct ksmbd_file *fp, char *buf, loff_t *pos,
> @@ -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 (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 = (int)v_len;
> goto out;
> }
>
> --
> 2.25.1
>


--

Thanks,
Hyunchul