The per hardif sysfs file "batman_adv/elp_interval" is using the generic functions to store/show uint values. The helper __batadv_store_uint_attr requires the softif net_device as parameter to print the resulting change as info text when the users writes to this file. It uses the helper function batadv_info to add it at the same time to the kernel ring buffer and to the batman-adv debug log (when CONFIG_BATMAN_ADV_DEBUG is enabled).

The function batadv_info requires as first parameter the batman-adv softif net_device. This parameter is then used to find the private buffer which contains the debug log for this batman-adv interface. But batadv_store_throughput_override used as first argument the slave net_device. This slave device doesn't have the batadv_priv private data which is access by batadv_info.

Writing to this file with CONFIG_BATMAN_ADV_DEBUG enabled can either lead to a segfault or to memory corruption.

Fixes: ec46535b8275 ("batman-adv: Add hard_iface specific sysfs wrapper macros for UINT") Signed-off-by: Sven Eckelmann sven@narfation.org --- v2:

* changed how ifname gets initialized (not sure why I've added \0)

net/batman-adv/sysfs.c | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/net/batman-adv/sysfs.c b/net/batman-adv/sysfs.c index 3a76e897..09427fc6 100644 --- a/net/batman-adv/sysfs.c +++ b/net/batman-adv/sysfs.c @@ -188,7 +188,8 @@ ssize_t batadv_store_##_name(struct kobject *kobj, \ \ return __batadv_store_uint_attr(buff, count, _min, _max, \ _post_func, attr, \ - &bat_priv->_var, net_dev); \ + &bat_priv->_var, net_dev, \ + NULL); \ }

#define BATADV_ATTR_SIF_SHOW_UINT(_name, _var) \ @@ -262,7 +263,9 @@ ssize_t batadv_store_##_name(struct kobject *kobj, \ \ length = __batadv_store_uint_attr(buff, count, _min, _max, \ _post_func, attr, \ - &hard_iface->_var, net_dev); \ + &hard_iface->_var, \ + hard_iface->soft_iface, \ + net_dev); \ \ batadv_hardif_put(hard_iface); \ return length; \ @@ -356,10 +359,12 @@ __batadv_store_bool_attr(char *buff, size_t count,

static int batadv_store_uint_attr(const char *buff, size_t count, struct net_device *net_dev, + struct net_device *slave_dev, const char *attr_name, unsigned int min, unsigned int max, atomic_t *attr) { + char ifname[IFNAMSIZ + 3] = ""; unsigned long uint_val; int ret;

@@ -385,8 +390,11 @@ static int batadv_store_uint_attr(const char *buff, size_t count, if (atomic_read(attr) == uint_val) return count;

- batadv_info(net_dev, "%s: Changing from: %i to: %lu\n", - attr_name, atomic_read(attr), uint_val); + if (slave_dev) + snprintf(ifname, sizeof(ifname), "%s: ", slave_dev->name); + + batadv_info(net_dev, "%s: %sChanging from: %i to: %lu\n", + attr_name, ifname, atomic_read(attr), uint_val);

atomic_set(attr, uint_val); return count; @@ -397,12 +405,13 @@ static ssize_t __batadv_store_uint_attr(const char *buff, size_t count, void (*post_func)(struct net_device *), const struct attribute *attr, atomic_t *attr_store, - struct net_device *net_dev) + struct net_device *net_dev, + struct net_device *slave_dev) { int ret;

- ret = batadv_store_uint_attr(buff, count, net_dev, attr->name, min, max, - attr_store); + ret = batadv_store_uint_attr(buff, count, net_dev, slave_dev, + attr->name, min, max, attr_store); if (post_func && ret) post_func(net_dev);

@@ -571,7 +580,7 @@ static ssize_t batadv_store_gw_sel_class(struct kobject *kobj, return __batadv_store_uint_attr(buff, count, 1, BATADV_TQ_MAX_VALUE, batadv_post_gw_reselect, attr, &bat_priv->gw.sel_class, - bat_priv->soft_iface); + bat_priv->soft_iface, NULL); }

static ssize_t batadv_show_gw_bwidth(struct kobject *kobj,