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| author | Nicolas Iooss <nicolas.iooss_linux@m4x.org> | 2015-07-17 16:23:45 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-07-17 16:39:53 -0700 |
| commit | 3958b79266b14729edd61daf9dfb84de45f4ec6d (patch) | |
| tree | 05990191af23a2632884358d40e173dfcb134219 /drivers | |
| parent | 8db1486065141e619e4855b84e350ef32064f7e1 (diff) | |
| download | linux-3958b79266b14729edd61daf9dfb84de45f4ec6d.tar.bz2 | |
configfs: fix kernel infoleak through user-controlled format string
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>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/usb/gadget/configfs.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c index 0495c94a23d7..289e20119fea 100644 --- a/drivers/usb/gadget/configfs.c +++ b/drivers/usb/gadget/configfs.c @@ -571,7 +571,7 @@ static struct config_group *function_make( if (IS_ERR(fi)) return ERR_CAST(fi); - ret = config_item_set_name(&fi->group.cg_item, name); + ret = config_item_set_name(&fi->group.cg_item, "%s", name); if (ret) { usb_put_function_instance(fi); return ERR_PTR(ret); |