Revision 28f300d23674fa01ae747c66ce861d4ee6aebe8c authored by Pavel Emelyanov on 19 September 2007, 05:46:45 UTC, committed by Linus Torvalds on 19 September 2007, 18:24:18 UTC
It turned out, that the user namespace is released during the do_exit() in
exit_task_namespaces(), but the struct user_struct is released only during the
put_task_struct(), i.e. MUCH later.
On debug kernels with poisoned slabs this will cause the oops in
uid_hash_remove() because the head of the chain, which resides inside the
struct user_namespace, will be already freed and poisoned.
Since the uid hash itself is required only when someone can search it, i.e.
when the namespace is alive, we can safely unhash all the user_struct-s from
it during the namespace exiting. The subsequent free_uid() will complete the
user_struct destruction.
For example simple program
#include <sched.h>
char stack[2 * 1024 * 1024];
int f(void *foo)
{
return 0;
}
int main(void)
{
clone(f, stack + 1 * 1024 * 1024, 0x10000000, 0);
return 0;
}
run on kernel with CONFIG_USER_NS turned on will oops the
kernel immediately.
This was spotted during OpenVZ kernel testing.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org>
Acked-by: "Serge E. Hallyn" <serue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 735de22
sysctl_net_x25.c
/* -*- linux-c -*-
* sysctl_net_x25.c: sysctl interface to net X.25 subsystem.
*
* Begun April 1, 1996, Mike Shaver.
* Added /proc/sys/net/x25 directory entry (empty =) ). [MS]
*/
#include <linux/sysctl.h>
#include <linux/skbuff.h>
#include <linux/socket.h>
#include <linux/netdevice.h>
#include <linux/init.h>
#include <net/x25.h>
static int min_timer[] = { 1 * HZ };
static int max_timer[] = { 300 * HZ };
static struct ctl_table_header *x25_table_header;
static struct ctl_table x25_table[] = {
{
.ctl_name = NET_X25_RESTART_REQUEST_TIMEOUT,
.procname = "restart_request_timeout",
.data = &sysctl_x25_restart_request_timeout,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec_minmax,
.strategy = &sysctl_intvec,
.extra1 = &min_timer,
.extra2 = &max_timer,
},
{
.ctl_name = NET_X25_CALL_REQUEST_TIMEOUT,
.procname = "call_request_timeout",
.data = &sysctl_x25_call_request_timeout,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec_minmax,
.strategy = &sysctl_intvec,
.extra1 = &min_timer,
.extra2 = &max_timer,
},
{
.ctl_name = NET_X25_RESET_REQUEST_TIMEOUT,
.procname = "reset_request_timeout",
.data = &sysctl_x25_reset_request_timeout,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec_minmax,
.strategy = &sysctl_intvec,
.extra1 = &min_timer,
.extra2 = &max_timer,
},
{
.ctl_name = NET_X25_CLEAR_REQUEST_TIMEOUT,
.procname = "clear_request_timeout",
.data = &sysctl_x25_clear_request_timeout,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec_minmax,
.strategy = &sysctl_intvec,
.extra1 = &min_timer,
.extra2 = &max_timer,
},
{
.ctl_name = NET_X25_ACK_HOLD_BACK_TIMEOUT,
.procname = "acknowledgement_hold_back_timeout",
.data = &sysctl_x25_ack_holdback_timeout,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec_minmax,
.strategy = &sysctl_intvec,
.extra1 = &min_timer,
.extra2 = &max_timer,
},
{
.ctl_name = NET_X25_FORWARD,
.procname = "x25_forward",
.data = &sysctl_x25_forward,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec,
},
{ 0, },
};
static struct ctl_table x25_dir_table[] = {
{
.ctl_name = NET_X25,
.procname = "x25",
.mode = 0555,
.child = x25_table,
},
{ 0, },
};
static struct ctl_table x25_root_table[] = {
{
.ctl_name = CTL_NET,
.procname = "net",
.mode = 0555,
.child = x25_dir_table,
},
{ 0, },
};
void __init x25_register_sysctl(void)
{
x25_table_header = register_sysctl_table(x25_root_table);
}
void x25_unregister_sysctl(void)
{
unregister_sysctl_table(x25_table_header);
}
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