Revision 3958b79266b14729edd61daf9dfb84de45f4ec6d authored by Nicolas Iooss on 17 July 2015, 23:23:45 UTC, committed by Linus Torvalds on 17 July 2015, 23:39:53 UTC
Some modules call config_item_init_type_name() and config_group_init_type_name() with parameter "name" directly controlled by userspace. These two functions call config_item_set_name() with this name used as a format string, which can be used to leak information such as content of the stack to userspace. For example, make_netconsole_target() in netconsole module calls config_item_init_type_name() with the name of a newly-created directory. This means that the following commands give some unexpected output, with configfs mounted in /sys/kernel/config/ and on a system with a configured eth0 ethernet interface: # modprobe netconsole # mkdir /sys/kernel/config/netconsole/target_%lx # echo eth0 > /sys/kernel/config/netconsole/target_%lx/dev_name # echo 1 > /sys/kernel/config/netconsole/target_%lx/enabled # echo eth0 > /sys/kernel/config/netconsole/target_%lx/dev_name # dmesg |tail -n1 [ 142.697668] netconsole: target (target_ffffffffc0ae8080) is enabled, disable to update parameters The directory name is correct but %lx has been interpreted in the internal item name, displayed here in the error message used by store_dev_name() in drivers/net/netconsole.c. To fix this, update every caller of config_item_set_name to use "%s" when operating on untrusted input. This issue was found using -Wformat-security gcc flag, once a __printf attribute has been added to config_item_set_name(). Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Acked-by: Felipe Balbi <balbi@ti.com> Acked-by: Joel Becker <jlbec@evilplan.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 8db1486
crypto_wq.c
/*
* Workqueue for crypto subsystem
*
* Copyright (c) 2009 Intel Corp.
* Author: Huang Ying <ying.huang@intel.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
*/
#include <linux/workqueue.h>
#include <linux/module.h>
#include <crypto/algapi.h>
#include <crypto/crypto_wq.h>
struct workqueue_struct *kcrypto_wq;
EXPORT_SYMBOL_GPL(kcrypto_wq);
static int __init crypto_wq_init(void)
{
kcrypto_wq = alloc_workqueue("crypto",
WQ_MEM_RECLAIM | WQ_CPU_INTENSIVE, 1);
if (unlikely(!kcrypto_wq))
return -ENOMEM;
return 0;
}
static void __exit crypto_wq_exit(void)
{
destroy_workqueue(kcrypto_wq);
}
subsys_initcall(crypto_wq_init);
module_exit(crypto_wq_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Workqueue for crypto subsystem");
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