Commit 579035dc authored by Andrew Vagin's avatar Andrew Vagin Committed by Linus Torvalds

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: default avatarAndrew Vagin <>
Acked-by: default avatarCyrill Gorcunov <>
Acked-by: default avatarOleg Nesterov <>
Cc: Eric W. Biederman <>
Cc: Pavel Emelyanov <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 35c448a8
......@@ -232,15 +232,19 @@ static int pid_ns_ctl_handler(struct ctl_table *table, int write,
*/ = &current->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,
{ }
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment