2016-11-21 05:47:42

by Oleg Drokin

Subject: [PATCH] staging/lustre: Use proper number of bytes in copy_from_user

From: Jian Yu <[email protected]>

This patch removes the usage of MAX_STRING_SIZE from
copy_from_user() and just copies enough bytes to cover
count passed in.

Signed-off-by: Jian Yu <[email protected]>
Reviewed-on: http://review.whamcloud.com/23462
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-8774
Reviewed-by: John L. Hammond <[email protected]>
Signed-off-by: Oleg Drokin <[email protected]>
---
drivers/staging/lustre/lustre/obdclass/lprocfs_status.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
index 8a2f02f3..db49992 100644
--- a/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
+++ b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
@@ -400,10 +400,17 @@ int lprocfs_wr_uint(struct file *file, const char __user *buffer,
char dummy[MAX_STRING_SIZE + 1], *end;
unsigned long tmp;

- dummy[MAX_STRING_SIZE] = '\0';
- if (copy_from_user(dummy, buffer, MAX_STRING_SIZE))
+ if (count >= sizeof(dummy))
+ return -EINVAL;
+
+ if (count == 0)
+ return 0;
+
+ if (copy_from_user(dummy, buffer, count))
return -EFAULT;

+ dummy[count] = '\0';
+
tmp = simple_strtoul(dummy, &end, 0);
if (dummy == end)
return -EINVAL;
--
2.7.4

2016-11-21 10:14:31

by Greg KH

Subject: Re: [PATCH] staging/lustre: Use proper number of bytes in copy_from_user

On Mon, Nov 21, 2016 at 12:46:48AM -0500, Oleg Drokin wrote:
> From: Jian Yu <[email protected]>
>
> This patch removes the usage of MAX_STRING_SIZE from
> copy_from_user() and just copies enough bytes to cover
> count passed in.
>
> Signed-off-by: Jian Yu <[email protected]>
> Reviewed-on: http://review.whamcloud.com/23462
> Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-8774
> Reviewed-by: John L. Hammond <[email protected]>
> Signed-off-by: Oleg Drokin <[email protected]>
> ---
> drivers/staging/lustre/lustre/obdclass/lprocfs_status.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
> index 8a2f02f3..db49992 100644
> --- a/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
> +++ b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
> @@ -400,10 +400,17 @@ int lprocfs_wr_uint(struct file *file, const char __user *buffer,
> char dummy[MAX_STRING_SIZE + 1], *end;
> unsigned long tmp;
>
> - dummy[MAX_STRING_SIZE] = '\0';
> - if (copy_from_user(dummy, buffer, MAX_STRING_SIZE))
> + if (count >= sizeof(dummy))
> + return -EINVAL;
> +
> + if (count == 0)
> + return 0;
> +
> + if (copy_from_user(dummy, buffer, count))
> return -EFAULT;
>
> + dummy[count] = '\0';
> +

You do know about simple_read_from_buffer(), right? I suggest using
those simple_* functions where ever you are touching user buffers, like
this code.

thanks,

greg k-h