From b9fd14c20871e6189f635e49b32d7789e430b3c8 Mon Sep 17 00:00:00 2001
From: Sven Eckelmann <sven@narfation.org>
Date: Fri, 31 Aug 2018 16:46:47 +0200
Subject: [PATCH] batman-adv: Fix segfault when writing to throughput_override
Git-commit: b9fd14c20871e6189f635e49b32d7789e430b3c8
Patch-mainline: v4.19-rc6
References: bsc#1051510
The per hardif sysfs file "batman_adv/throughput_override" prints 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: 0b5ecc6811bd ("batman-adv: add throughput override attribute to hard_ifaces")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Acked-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
net/batman-adv/sysfs.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/net/batman-adv/sysfs.c b/net/batman-adv/sysfs.c
index f2eef43bd2ec..3a76e8970c02 100644
--- a/net/batman-adv/sysfs.c
+++ b/net/batman-adv/sysfs.c
@@ -1090,8 +1090,9 @@ static ssize_t batadv_store_throughput_override(struct kobject *kobj,
if (old_tp_override == tp_override)
goto out;
- batadv_info(net_dev, "%s: Changing from: %u.%u MBit to: %u.%u MBit\n",
- "throughput_override",
+ batadv_info(hard_iface->soft_iface,
+ "%s: %s: Changing from: %u.%u MBit to: %u.%u MBit\n",
+ "throughput_override", net_dev->name,
old_tp_override / 10, old_tp_override % 10,
tp_override / 10, tp_override % 10);
--
2.18.0