[PATCH] net/ethernet/intel/ixgbe/ixgbe_debugfs.c: fix error handling in ixgbe_dbg_reg_ops_read().

[Cyril Roelandt]

copy_to_user() cannot return a negative value: it returns the number of bytes
that could not be copied.

Return -EFAULT on failure rather than the number of bytes that could not be
copied, as this seems more standard.

Signed-off-by: Cyril Roelandt <tipe...@gmail.com>
---
drivers/net/ethernet/intel/ixgbe/ixgbe_debugfs.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_debugfs.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_debugfs.c
index 8d3a218..77a3598 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_debugfs.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_debugfs.c
@@ -62,7 +62,6 @@ static ssize_t ixgbe_dbg_reg_ops_read(struct file *filp, char __user *buffer,
{
struct ixgbe_adapter *adapter = filp->private_data;
char buf[256];
- int bytes_not_copied;
int len;

/* don't allow partial reads */
@@ -73,9 +72,8 @@ static ssize_t ixgbe_dbg_reg_ops_read(struct file *filp, char __user *buffer,
adapter->netdev->name, ixgbe_dbg_reg_ops_buf);
if (count < len)
return -ENOSPC;
- bytes_not_copied = copy_to_user(buffer, buf, len);
- if (bytes_not_copied < 0)
- return bytes_not_copied;
+ if (copy_to_user(buffer, buf, len) > 0)
+ return -EFAULT;

*ppos = len;
return len;
--
1.7.10.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majo...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

[Jeff Kirsher]

On Fri, 2012-11-16 at 04:26 +0100, Cyril Roelandt wrote:
>
> copy_to_user() cannot return a negative value: it returns the number
> of bytes
> that could not be copied.
>
> Return -EFAULT on failure rather than the number of bytes that could
> not be
> copied, as this seems more standard.
>
> Signed-off-by: Cyril Roelandt <tipe...@gmail.com>
> ---
> drivers/net/ethernet/intel/ixgbe/ixgbe_debugfs.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)

Actually, I already have a similar patch in my queue reported by Dan
Carpenter, and created by Josh Hay which fixes this issue. I should be
pushing the patch in my queue in the next week. Here is the patch I am
referring to:

ixgbe: eliminate Smatch warnings in ixgbe_debugfs.c

This patch replaces calls to copy_to_user, copy_from_user, and the
associated logic, with calls to simple_read_from_buffer and
simple_write_to_buffer respectively. This was done to eliminate
warnings generated by the Smatch static analysis tool.

Reported-by: Dan Carpenter <dan.ca...@oracle.com>
CC: Dan Carpenter <dan.ca...@oracle.com>
Signed-off-by: Josh Hay <joshua...@intel.com>

Cheers,
Jeff