Revision 85bd839983778fcd0c1c043327b14a046e979b39 authored by Gu Zheng on 10 June 2015, 18:14:43 UTC, committed by Linus Torvalds on 10 June 2015, 23:43:43 UTC
Izumi found the following oops when hot re-adding a node:

    BUG: unable to handle kernel paging request at ffffc90008963690
    IP: __wake_up_bit+0x20/0x70
    Oops: 0000 [#1] SMP
    CPU: 68 PID: 1237 Comm: rs:main Q:Reg Not tainted 4.1.0-rc5 #80
    Hardware name: FUJITSU PRIMEQUEST2800E/SB, BIOS PRIMEQUEST 2000 Series BIOS Version 1.87 04/28/2015
    task: ffff880838df8000 ti: ffff880017b94000 task.ti: ffff880017b94000
    RIP: 0010:[<ffffffff810dff80>]  [<ffffffff810dff80>] __wake_up_bit+0x20/0x70
    RSP: 0018:ffff880017b97be8  EFLAGS: 00010246
    RAX: ffffc90008963690 RBX: 00000000003c0000 RCX: 000000000000a4c9
    RDX: 0000000000000000 RSI: ffffea101bffd500 RDI: ffffc90008963648
    RBP: ffff880017b97c08 R08: 0000000002000020 R09: 0000000000000000
    R10: 0000000000000000 R11: 0000000000000000 R12: ffff8a0797c73800
    R13: ffffea101bffd500 R14: 0000000000000001 R15: 00000000003c0000
    FS:  00007fcc7ffff700(0000) GS:ffff880874800000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: ffffc90008963690 CR3: 0000000836761000 CR4: 00000000001407e0
    Call Trace:
      unlock_page+0x6d/0x70
      generic_write_end+0x53/0xb0
      xfs_vm_write_end+0x29/0x80 [xfs]
      generic_perform_write+0x10a/0x1e0
      xfs_file_buffered_aio_write+0x14d/0x3e0 [xfs]
      xfs_file_write_iter+0x79/0x120 [xfs]
      __vfs_write+0xd4/0x110
      vfs_write+0xac/0x1c0
      SyS_write+0x58/0xd0
      system_call_fastpath+0x12/0x76
    Code: 5d c3 66 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 48 83 ec 20 65 48 8b 04 25 28 00 00 00 48 89 45 f8 31 c0 48 8d 47 48 <48> 39 47 48 48 c7 45 e8 00 00 00 00 48 c7 45 f0 00 00 00 00 48
    RIP  [<ffffffff810dff80>] __wake_up_bit+0x20/0x70
     RSP <ffff880017b97be8>
    CR2: ffffc90008963690

Reproduce method (re-add a node)::
  Hot-add nodeA --> remove nodeA --> hot-add nodeA (panic)

This seems an use-after-free problem, and the root cause is
zone->wait_table was not set to *NULL* after free it in
try_offline_node.

When hot re-add a node, we will reuse the pgdat of it, so does the zone
struct, and when add pages to the target zone, it will init the zone
first (including the wait_table) if the zone is not initialized.  The
judgement of zone initialized is based on zone->wait_table:

	static inline bool zone_is_initialized(struct zone *zone)
	{
		return !!zone->wait_table;
	}

so if we do not set the zone->wait_table to *NULL* after free it, the
memory hotplug routine will skip the init of new zone when hot re-add
the node, and the wait_table still points to the freed memory, then we
will access the invalid address when trying to wake up the waiting
people after the i/o operation with the page is done, such as mentioned
above.

Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Reported-by: Taku Izumi <izumi.taku@jp.fujitsu.com>
Reviewed by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 5879ae5
Raw File
proc.c
/*
 * Scatterlist Cryptographic API.
 *
 * Procfs information.
 *
 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
 * Copyright (c) 2005 Herbert Xu <herbert@gondor.apana.org.au>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option) 
 * any later version.
 *
 */

#include <linux/atomic.h>
#include <linux/init.h>
#include <linux/crypto.h>
#include <linux/module.h>	/* for module_name() */
#include <linux/rwsem.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/sysctl.h>
#include "internal.h"

#ifdef CONFIG_CRYPTO_FIPS
static struct ctl_table crypto_sysctl_table[] = {
	{
		.procname       = "fips_enabled",
		.data           = &fips_enabled,
		.maxlen         = sizeof(int),
		.mode           = 0444,
		.proc_handler   = proc_dointvec
	},
	{}
};

static struct ctl_table crypto_dir_table[] = {
	{
		.procname       = "crypto",
		.mode           = 0555,
		.child          = crypto_sysctl_table
	},
	{}
};

static struct ctl_table_header *crypto_sysctls;

static void crypto_proc_fips_init(void)
{
	crypto_sysctls = register_sysctl_table(crypto_dir_table);
}

static void crypto_proc_fips_exit(void)
{
	if (crypto_sysctls)
		unregister_sysctl_table(crypto_sysctls);
}
#else
#define crypto_proc_fips_init()
#define crypto_proc_fips_exit()
#endif

static void *c_start(struct seq_file *m, loff_t *pos)
{
	down_read(&crypto_alg_sem);
	return seq_list_start(&crypto_alg_list, *pos);
}

static void *c_next(struct seq_file *m, void *p, loff_t *pos)
{
	return seq_list_next(p, &crypto_alg_list, pos);
}

static void c_stop(struct seq_file *m, void *p)
{
	up_read(&crypto_alg_sem);
}

static int c_show(struct seq_file *m, void *p)
{
	struct crypto_alg *alg = list_entry(p, struct crypto_alg, cra_list);
	
	seq_printf(m, "name         : %s\n", alg->cra_name);
	seq_printf(m, "driver       : %s\n", alg->cra_driver_name);
	seq_printf(m, "module       : %s\n", module_name(alg->cra_module));
	seq_printf(m, "priority     : %d\n", alg->cra_priority);
	seq_printf(m, "refcnt       : %d\n", atomic_read(&alg->cra_refcnt));
	seq_printf(m, "selftest     : %s\n",
		   (alg->cra_flags & CRYPTO_ALG_TESTED) ?
		   "passed" : "unknown");
	seq_printf(m, "internal     : %s\n",
		   (alg->cra_flags & CRYPTO_ALG_INTERNAL) ?
		   "yes" : "no");

	if (alg->cra_flags & CRYPTO_ALG_LARVAL) {
		seq_printf(m, "type         : larval\n");
		seq_printf(m, "flags        : 0x%x\n", alg->cra_flags);
		goto out;
	}

	if (alg->cra_type && alg->cra_type->show) {
		alg->cra_type->show(m, alg);
		goto out;
	}
	
	switch (alg->cra_flags & (CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_LARVAL)) {
	case CRYPTO_ALG_TYPE_CIPHER:
		seq_printf(m, "type         : cipher\n");
		seq_printf(m, "blocksize    : %u\n", alg->cra_blocksize);
		seq_printf(m, "min keysize  : %u\n",
					alg->cra_cipher.cia_min_keysize);
		seq_printf(m, "max keysize  : %u\n",
					alg->cra_cipher.cia_max_keysize);
		break;
	case CRYPTO_ALG_TYPE_COMPRESS:
		seq_printf(m, "type         : compression\n");
		break;
	default:
		seq_printf(m, "type         : unknown\n");
		break;
	}

out:
	seq_putc(m, '\n');
	return 0;
}

static const struct seq_operations crypto_seq_ops = {
	.start		= c_start,
	.next		= c_next,
	.stop		= c_stop,
	.show		= c_show
};

static int crypto_info_open(struct inode *inode, struct file *file)
{
	return seq_open(file, &crypto_seq_ops);
}
        
static const struct file_operations proc_crypto_ops = {
	.open		= crypto_info_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= seq_release
};

void __init crypto_init_proc(void)
{
	proc_create("crypto", 0, NULL, &proc_crypto_ops);
	crypto_proc_fips_init();
}

void __exit crypto_exit_proc(void)
{
	crypto_proc_fips_exit();
	remove_proc_entry("crypto", NULL);
}
back to top