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authorDmitry Safonov <dima@arista.com>2020-04-06 18:13:42 +0100
committerThomas Gleixner <tglx@linutronix.de>2020-04-07 12:37:21 +0200
commiteeec26d5da8248ea4e240b8795bb4364213d3247 (patch)
tree2e1aef9815026c6d771813a7216a531c8cba33cd /Documentation
parentb801f1e22c23c259d6a2c955efddd20370de19a6 (diff)
downloadlinux-eeec26d5da8248ea4e240b8795bb4364213d3247.tar.gz
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) <mtk.manpages@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Andrei Vagin <avagin@gmail.com>
Acked-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: stable@kernel.org
Link: https://lkml.kernel.org/r/20200406171342.128733-1-dima@arista.com

Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/admin-guide/sysctl/user.rst6
1 files changed, 6 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
 ===================