[PATCH net-next] ethtool: copy reglen to userspace

From: Vivien Didelot
Date: Tue May 28 2019 - 17:02:24 EST


ethtool_get_regs() allocates a buffer of size reglen obtained from
ops->get_regs_len(), thus only this value must be used when copying
the buffer back to userspace. Also no need to check regbuf twice.

Signed-off-by: Vivien Didelot <vivien.didelot@xxxxxxxxx>
---
net/core/ethtool.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 4a593853cbf2..f3369f31d93a 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -1338,38 +1338,38 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
static int ethtool_get_regs(struct net_device *dev, char __user *useraddr)
{
struct ethtool_regs regs;
const struct ethtool_ops *ops = dev->ethtool_ops;
void *regbuf;
int reglen, ret;

if (!ops->get_regs || !ops->get_regs_len)
return -EOPNOTSUPP;

if (copy_from_user(&regs, useraddr, sizeof(regs)))
return -EFAULT;

reglen = ops->get_regs_len(dev);
if (reglen <= 0)
return reglen;

if (regs.len > reglen)
regs.len = reglen;

regbuf = vzalloc(reglen);
if (!regbuf)
return -ENOMEM;

ops->get_regs(dev, &regs, regbuf);

ret = -EFAULT;
if (copy_to_user(useraddr, &regs, sizeof(regs)))
goto out;
useraddr += offsetof(struct ethtool_regs, data);
- if (regbuf && copy_to_user(useraddr, regbuf, regs.len))
+ if (copy_to_user(useraddr, regbuf, reglen))
goto out;
ret = 0;

out:
vfree(regbuf);
return ret;
}
--
2.21.0