From 579035dc5ddd6d48fd8529e7358b03d911ab9d8a Mon Sep 17 00:00:00 2001 From: Andrew Vagin Date: Mon, 17 Sep 2012 14:09:12 -0700 Subject: [PATCH] pid-namespace: limit value of ns_last_pid to (0, max_pid) The kernel doesn't check the pid for negative values, so if you try to write -2 to /proc/sys/kernel/ns_last_pid, you will get a kernel panic. The crash happens because the next pid is -1, and alloc_pidmap() will try to access to a nonexistent pidmap. map = &pid_ns->pidmap[pid/BITS_PER_PAGE]; Signed-off-by: Andrew Vagin Acked-by: Cyrill Gorcunov Acked-by: Oleg Nesterov Cc: Eric W. Biederman Cc: Pavel Emelyanov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/pid_namespace.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c index b3c7fd554250..6144bab8fd8e 100644 --- a/kernel/pid_namespace.c +++ b/kernel/pid_namespace.c @@ -232,15 +232,19 @@ static int pid_ns_ctl_handler(struct ctl_table *table, int write, */ tmp.data = ¤t->nsproxy->pid_ns->last_pid; - return proc_dointvec(&tmp, write, buffer, lenp, ppos); + return proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos); } +extern int pid_max; +static int zero = 0; static struct ctl_table pid_ns_ctl_table[] = { { .procname = "ns_last_pid", .maxlen = sizeof(int), .mode = 0666, /* permissions are checked in the handler */ .proc_handler = pid_ns_ctl_handler, + .extra1 = &zero, + .extra2 = &pid_max, }, { } }; -- 2.20.1