The patch titled
Subject: configfs: fix kernel infoleak through user-controlled format string
has been added to the -mm tree. Its filename is
configfs-fix-kernel-infoleak-through-user-controlled-format-string.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/configfs-fix-kernel-infoleak-through-user-controlled-format-string.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/configfs-fix-kernel-infoleak-through-user-controlled-format-string.patch
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------------------------------------------------------
From: Nicolas Iooss <nicolas.iooss_linux@xxxxxxx>
Subject: 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@xxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Felipe Balbi <balbi@xxxxxx>
Cc: Joel Becker <jlbec@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/usb/gadget/configfs.c | 2 +-
fs/configfs/item.c | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)
diff -puN drivers/usb/gadget/configfs.c~configfs-fix-kernel-infoleak-through-user-controlled-format-string drivers/usb/gadget/configfs.c
--- a/drivers/usb/gadget/configfs.c~configfs-fix-kernel-infoleak-through-user-controlled-format-string
+++ a/drivers/usb/gadget/configfs.c
@@ -571,7 +571,7 @@ static struct config_group *function_mak
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);
diff -puN fs/configfs/item.c~configfs-fix-kernel-infoleak-through-user-controlled-format-string fs/configfs/item.c
--- a/fs/configfs/item.c~configfs-fix-kernel-infoleak-through-user-controlled-format-string
+++ a/fs/configfs/item.c
@@ -115,7 +115,7 @@ void config_item_init_type_name(struct c
const char *name,
struct config_item_type *type)
{
- config_item_set_name(item, name);
+ config_item_set_name(item, "%s", name);
item->ci_type = type;
config_item_init(item);
}
@@ -124,7 +124,7 @@ EXPORT_SYMBOL(config_item_init_type_name
void config_group_init_type_name(struct config_group *group, const char *name,
struct config_item_type *type)
{
- config_item_set_name(&group->cg_item, name);
+ config_item_set_name(&group->cg_item, "%s", name);
group->cg_item.ci_type = type;
config_group_init(group);
}
_
Patches currently in -mm which might be from nicolas.iooss_linux@xxxxxxx are
include-lib-add-__printf-attributes-to-several-function-prototypes.patch
configfs-fix-kernel-infoleak-through-user-controlled-format-string.patch
linux-next.patch
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