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authorDmitry Safonov <[email protected]>2020-04-06 18:13:42 +0100
committerThomas Gleixner <[email protected]>2020-04-07 12:37:21 +0200
commiteeec26d5da8248ea4e240b8795bb4364213d3247 (patch)
tree2e1aef9815026c6d771813a7216a531c8cba33cd
parentb801f1e22c23c259d6a2c955efddd20370de19a6 (diff)
time/namespace: Add max_time_namespaces ucount
Michael noticed that userns limit for number of time namespaces is missing. Furthermore, time namespace introduced UCOUNT_TIME_NAMESPACES, but didn't introduce an array member in user_table[]. It would make array's initialisation OOB write, but by luck the user_table array has an excessive empty member (all accesses to the array are limited with UCOUNT_COUNTS - so it silently reuses the last free member. Fixes user-visible regression: max_inotify_instances by reason of the missing UCOUNT_ENTRY() has limited max number of namespaces instead of the number of inotify instances. Fixes: 769071ac9f20 ("ns: Introduce Time Namespace") Reported-by: Michael Kerrisk (man-pages) <[email protected]> Signed-off-by: Dmitry Safonov <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Acked-by: Andrei Vagin <[email protected]> Acked-by: Vincenzo Frascino <[email protected]> Cc: [email protected] Link: https://lkml.kernel.org/r/[email protected]
-rw-r--r--Documentation/admin-guide/sysctl/user.rst6
-rw-r--r--kernel/ucount.c1
2 files changed, 7 insertions, 0 deletions
diff --git a/Documentation/admin-guide/sysctl/user.rst b/Documentation/admin-guide/sysctl/user.rst
index 650eaa03f15e..c45824589339 100644
--- a/Documentation/admin-guide/sysctl/user.rst
+++ b/Documentation/admin-guide/sysctl/user.rst
@@ -65,6 +65,12 @@ max_pid_namespaces
The maximum number of pid namespaces that any user in the current
user namespace may create.
+max_time_namespaces
+===================
+
+ The maximum number of time namespaces that any user in the current
+ user namespace may create.
+
max_user_namespaces
===================
diff --git a/kernel/ucount.c b/kernel/ucount.c
index a53cc2b4179c..29c60eb4ec9b 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -69,6 +69,7 @@ static struct ctl_table user_table[] = {
UCOUNT_ENTRY("max_net_namespaces"),
UCOUNT_ENTRY("max_mnt_namespaces"),
UCOUNT_ENTRY("max_cgroup_namespaces"),
+ UCOUNT_ENTRY("max_time_namespaces"),
#ifdef CONFIG_INOTIFY_USER
UCOUNT_ENTRY("max_inotify_instances"),
UCOUNT_ENTRY("max_inotify_watches"),