Commit 844c6fdc authored by Zhihao Cheng's avatar Zhihao Cheng Committed by Richard Weinberger
Browse files

ubi: Revert "ubi: wl: Close down wear-leveling before nand is suspended" 

Commit 5580cdae ("ubi: wl: Close down wear-leveling before nand is
suspended") added a reboot notification in UBI layer to shutdown the
wear-leveling subsystem, which imported an UAF problem[1]. Besides that,
the method also brings other potential UAF problems, for example:
       reboot             kworker
 ubi_wl_reboot_notifier
  ubi_wl_close
   ubi_fastmap_close
    kfree(ubi->fm)
                     update_fastmap_work_fn
		      ubi_update_fastmap
		       old_fm = ubi->fm
		       if (old_fm && old_fm->e[i]) // UAF!

Actually, the problem fixed by commit 5580cdae ("ubi: wl: Close down
wear-leveling before nand is suspended") has been solved by commit
8cba3234 ("mtd: rawnand: protect access to rawnand devices while in
suspend"), which was discussed in [2]. So we can revert the commit
5580cdae ("ubi: wl: Close down wear-leveling before nand is
suspended") directly.

[1] https://lore.kernel.org/linux-mtd/20241208175211.9406-2-dennis.lamerice@gmail.com/
[2] https://lore.kernel.org/all/9bf76f5d-12a4-46ff-90d4-4a7f0f47c381@axis.com/



Fixes: 5580cdae ("ubi: wl: Close down wear-leveling before nand is suspended")
Reported-by: default avatarDennis Lam <dennis.lamerice@gmail.com>
Closes: https://lore.kernel.org/linux-mtd/20241208175211.9406-2-dennis.lamerice@gmail.com/


Signed-off-by: default avatarZhihao Cheng <chengzhihao1@huawei.com>
Acked-by: default avatarMårten Lindahl <marten.lindahl@axis.com>
Signed-off-by: default avatarRichard Weinberger <richard@nod.at>
parent 404de7ab

drivers/mtd/ubi/ubi.h

+0 −2
Original line number Diff line number Diff line
@@ -549,7 +549,6 @@ struct ubi_debug_info { 
 * @peb_buf: a buffer of PEB size used for different purposes

 * @buf_mutex: protects @peb_buf

 * @ckvol_mutex: serializes static volume checking when opening

 * @wl_reboot_notifier: close all wear-leveling work before reboot

 *

 * @dbg: debugging information for this UBI device

 */
@@ -652,7 +651,6 @@ struct ubi_device { 
	void *peb_buf;

	struct mutex buf_mutex;

	struct mutex ckvol_mutex;

	struct notifier_block wl_reboot_notifier;



	struct ubi_debug_info dbg;

};

drivers/mtd/ubi/wl.c

+0 −21
Original line number Diff line number Diff line
@@ -89,7 +89,6 @@ 
#include <linux/crc32.h>

#include <linux/freezer.h>

#include <linux/kthread.h>

#include <linux/reboot.h>

#include "ubi.h"

#include "wl.h"
@@ -128,8 +127,6 @@ static int self_check_in_wl_tree(const struct ubi_device *ubi, 
				 struct ubi_wl_entry *e, struct rb_root *root);

static int self_check_in_pq(const struct ubi_device *ubi,

			    struct ubi_wl_entry *e);

static int ubi_wl_reboot_notifier(struct notifier_block *n,

				  unsigned long state, void *cmd);



/**

 * wl_tree_add - add a wear-leveling entry to a WL RB-tree.
@@ -1953,13 +1950,6 @@ int ubi_wl_init(struct ubi_device *ubi, struct ubi_attach_info *ai) 
	if (!ubi->ro_mode && !ubi->fm_disabled)

		ubi_ensure_anchor_pebs(ubi);

#endif



	if (!ubi->wl_reboot_notifier.notifier_call) {

		ubi->wl_reboot_notifier.notifier_call = ubi_wl_reboot_notifier;

		ubi->wl_reboot_notifier.priority = 1; /* Higher than MTD */

		register_reboot_notifier(&ubi->wl_reboot_notifier);

	}



	return 0;



out_free:
@@ -2005,17 +1995,6 @@ void ubi_wl_close(struct ubi_device *ubi) 
	kfree(ubi->lookuptbl);

}



static int ubi_wl_reboot_notifier(struct notifier_block *n,

				  unsigned long state, void *cmd)

{

	struct ubi_device *ubi;



	ubi = container_of(n, struct ubi_device, wl_reboot_notifier);

	ubi_wl_close(ubi);



	return NOTIFY_DONE;

}



/**

 * self_check_ec - make sure that the erase counter of a PEB is correct.

 * @ubi: UBI device description object