batman-adv: Fix segfault when writing to sysfs elp_interval

[ Upstream commit a25bab9d723a08bd0bdafb1529faf9094c690b70 ]

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: 0744ff8fa8fa ("batman-adv: Add hard_iface specific sysfs wrapper macros for UINT")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Acked-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/batman-adv/sysfs.c b/net/batman-adv/sysfs.c
index ec412c5..2ef9b13 100644 (file)
--- a/net/batman-adv/sysfs.c
+++ b/net/batman-adv/sysfs.c
@@ -186,7 +186,8 @@ 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)                         \
@@ -260,7 +261,9 @@ 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;                                                  \
@@ -354,10 +357,12 @@ __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;
 
@@ -383,8 +388,11 @@ 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;
@@ -395,12 +403,13 @@ 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);
 
@@ -569,7 +578,7 @@ 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,