Commit a25bab9d authored by Sven Eckelmann's avatar Sven Eckelmann Committed by Simon Wunderlich
Browse files

batman-adv: Fix segfault when writing to sysfs elp_interval

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: 0744ff8f

 ("batman-adv: Add hard_iface specific sysfs wrapper macros for UINT")
Signed-off-by: default avatarSven Eckelmann <>
Acked-by: default avatarMarek Lindner <>
Signed-off-by: default avatarSimon Wunderlich <>
parent b9fd14c2
......@@ -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,
ret = batadv_store_uint_attr(buff, count, net_dev, slave_dev,
attr->name, min, max, attr_store);
if (post_func && ret)
......@@ -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->soft_iface, NULL);
static ssize_t batadv_show_gw_bwidth(struct kobject *kobj,
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