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net-sysfs: use dev_addr_sem to remove races in address_show()

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Using dev_base_lock is not preventing from reading garbage.

Use dev_addr_sem instead.

v4: place dev_addr_sem extern in net/core/dev.h (Jakub Kicinski)
 Link: https://lore.kernel.org/netdev/20240212175845.10f6680a@kernel.org/

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2024-02-13 06:32:38 +00:00
committed by David S. Miller
parent 12692e3df2
commit c7d52737e7
3 changed files with 11 additions and 4 deletions
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10
net/core/net-sysfs.c
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@ -142,17 +142,21 @@ static ssize_t name_assign_type_show(struct device *dev,
}
static DEVICE_ATTR_RO(name_assign_type);
/* use same locking rules as GIFHWADDR ioctl's */
/* use same locking rules as GIFHWADDR ioctl's (dev_get_mac_address()) */
static ssize_t address_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct net_device *ndev = to_net_dev(dev);
ssize_t ret = -EINVAL;
read_lock(&dev_base_lock);
down_read(&dev_addr_sem);
rcu_read_lock();
if (dev_isalive(ndev))
ret = sysfs_format_mac(buf, ndev->dev_addr, ndev->addr_len);
read_unlock(&dev_base_lock);
rcu_read_unlock();
up_read(&dev_addr_sem);
return ret;
}
static DEVICE_ATTR_RO(address);