diff mbox series

[maint,1/2] batman-adv: Fix segfault when writing to throughput_override

Message ID 20180831144648.24032-1-sven@narfation.org (mailing list archive)
State Accepted, archived
Commit ddf99b78e255530cbadc0f67656a549e19520280
Delegated to: Simon Wunderlich
Headers
Series [maint,1/2] batman-adv: Fix segfault when writing to throughput_override |

Commit Message

Sven Eckelmann Aug. 31, 2018, 2:46 p.m. UTC 
  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: c513176e4b7a ("batman-adv: add throughput override attribute to hard_ifaces")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
 net/batman-adv/sysfs.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Comments

Marek Lindner Sept. 5, 2018, 10:55 a.m. UTC | #1 
On Friday, 31 August 2018 22:46:47 HKT Sven Eckelmann wrote:
> 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: c513176e4b7a ("batman-adv: add throughput override attribute to
> hard_ifaces") Signed-off-by: Sven Eckelmann <sven@narfation.org>


Acked-by: Marek Lindner <mareklindner@neomailbox.ch>

Cheers,
Marek
Sven Eckelmann Sept. 5, 2018, 4:07 p.m. UTC | #2 
On Freitag, 31. August 2018 16:46:47 CEST Sven Eckelmann wrote:
> 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.
[...]

Added both patches as ddf99b78e255 [1] and 848be9859b01 [2]

Kind regards,
	Sven

[1] https://git.open-mesh.org/batman-adv.git/commit/ddf99b78e255530cbadc0f67656a549e19520280
[2] https://git.open-mesh.org/batman-adv.git/commit/848be9859b0109a6e428f92f21f2e660153b1c75
diff mbox series

Patch

diff --git a/net/batman-adv/sysfs.c b/net/batman-adv/sysfs.c
index f2eef43b..3a76e897 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);