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27 March 2024, 02:37:15 UTC
Revision 070c43eea5043e950daa423707ae3c77e2f48edb authored by Thiago Jung Bauermann on 01 September 2016, 23:14:44 UTC, committed by Linus Torvalds on 02 September 2016, 00:52:01 UTC 
kexec: fix double-free when failing to relocate the purgatory
 
If kexec_apply_relocations fails, kexec_load_purgatory frees pi->sechdrs
and pi->purgatory_buf.  This is redundant, because in case of error
kimage_file_prepare_segments calls kimage_file_post_load_cleanup, which
will also free those buffers.

This causes two warnings like the following, one for pi->sechdrs and the
other for pi->purgatory_buf:

  kexec-bzImage64: Loading purgatory failed
  ------------[ cut here ]------------
  WARNING: CPU: 1 PID: 2119 at mm/vmalloc.c:1490 __vunmap+0xc1/0xd0
  Trying to vfree() nonexistent vm area (ffffc90000e91000)
  Modules linked in:
  CPU: 1 PID: 2119 Comm: kexec Not tainted 4.8.0-rc3+ #5
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
  Call Trace:
    dump_stack+0x4d/0x65
    __warn+0xcb/0xf0
    warn_slowpath_fmt+0x4f/0x60
    ? find_vmap_area+0x19/0x70
    ? kimage_file_post_load_cleanup+0x47/0xb0
    __vunmap+0xc1/0xd0
    vfree+0x2e/0x70
    kimage_file_post_load_cleanup+0x5e/0xb0
    SyS_kexec_file_load+0x448/0x680
    ? putname+0x54/0x60
    ? do_sys_open+0x190/0x1f0
    entry_SYSCALL_64_fastpath+0x13/0x8f
  ---[ end trace 158bb74f5950ca2b ]---

Fix by setting pi->sechdrs an pi->purgatory_buf to NULL, since vfree
won't try to free a NULL pointer.

Link: http://lkml.kernel.org/r/1472083546-23683-1-git-send-email-bauerman@linux.vnet.ibm.com
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Dave Young <dyoung@redhat.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 6b4e318
Raw File
Tip revision: 070c43eea5043e950daa423707ae3c77e2f48edb authored by Thiago Jung Bauermann on 01 September 2016, 23:14:44 UTC
kexec: fix double-free when failing to relocate the purgatory
Tip revision: 070c43e
blk-mq-cpu.c 
/*
 * CPU notifier helper code for blk-mq
 *
 * Copyright (C) 2013-2014 Jens Axboe
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/list.h>
#include <linux/llist.h>
#include <linux/smp.h>
#include <linux/cpu.h>

#include <linux/blk-mq.h>
#include "blk-mq.h"

static LIST_HEAD(blk_mq_cpu_notify_list);
static DEFINE_RAW_SPINLOCK(blk_mq_cpu_notify_lock);

static int blk_mq_main_cpu_notify(struct notifier_block *self,
				  unsigned long action, void *hcpu)
{
	unsigned int cpu = (unsigned long) hcpu;
	struct blk_mq_cpu_notifier *notify;
	int ret = NOTIFY_OK;

	raw_spin_lock(&blk_mq_cpu_notify_lock);

	list_for_each_entry(notify, &blk_mq_cpu_notify_list, list) {
		ret = notify->notify(notify->data, action, cpu);
		if (ret != NOTIFY_OK)
			break;
	}

	raw_spin_unlock(&blk_mq_cpu_notify_lock);
	return ret;
}

void blk_mq_register_cpu_notifier(struct blk_mq_cpu_notifier *notifier)
{
	BUG_ON(!notifier->notify);

	raw_spin_lock(&blk_mq_cpu_notify_lock);
	list_add_tail(&notifier->list, &blk_mq_cpu_notify_list);
	raw_spin_unlock(&blk_mq_cpu_notify_lock);
}

void blk_mq_unregister_cpu_notifier(struct blk_mq_cpu_notifier *notifier)
{
	raw_spin_lock(&blk_mq_cpu_notify_lock);
	list_del(&notifier->list);
	raw_spin_unlock(&blk_mq_cpu_notify_lock);
}

void blk_mq_init_cpu_notifier(struct blk_mq_cpu_notifier *notifier,
			      int (*fn)(void *, unsigned long, unsigned int),
			      void *data)
{
	notifier->notify = fn;
	notifier->data = data;
}

void __init blk_mq_cpu_init(void)
{
	hotcpu_notifier(blk_mq_main_cpu_notify, 0);
}
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