From 3534e5a5ed2997ca1b00f44a0378a075bd05e8a3 Mon Sep 17 00:00:00 2001

From: Luo Meng <luomeng12@huawei.com>

Date: Thu, 14 Jul 2022 19:28:25 +0800

Subject: [PATCH] dm thin: fix use-after-free crash in

 dm_sm_register_threshold_callback

Git-commit: 3534e5a5ed2997ca1b00f44a0378a075bd05e8a3

Patch-mainline: v6.0-rc1

References: git-fixes

Fault inject on pool metadata device reports:

  BUG: KASAN: use-after-free in dm_pool_register_metadata_threshold+0x40/0x80

  Read of size 8 at addr ffff8881b9d50068 by task dmsetup/950

  CPU: 7 PID: 950 Comm: dmsetup Tainted: G        W         5.19.0-rc6 #1

  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1.fc33 04/01/2014

  Call Trace:

   <TASK>

   dump_stack_lvl+0x34/0x44

   print_address_description.constprop.0.cold+0xeb/0x3f4

   kasan_report.cold+0xe6/0x147

   dm_pool_register_metadata_threshold+0x40/0x80

   pool_ctr+0xa0a/0x1150

   dm_table_add_target+0x2c8/0x640

   table_load+0x1fd/0x430

   ctl_ioctl+0x2c4/0x5a0

   dm_ctl_ioctl+0xa/0x10

   __x64_sys_ioctl+0xb3/0xd0

   do_syscall_64+0x35/0x80

   entry_SYSCALL_64_after_hwframe+0x46/0xb0

This can be easily reproduced using:

  echo offline > /sys/block/sda/device/state

  dd if=/dev/zero of=/dev/mapper/thin bs=4k count=10

  dmsetup load pool --table "0 20971520 thin-pool /dev/sda /dev/sdb 128 0 0"

If a metadata commit fails, the transaction will be aborted and the

metadata space maps will be destroyed. If a DM table reload then

happens for this failed thin-pool, a use-after-free will occur in

dm_sm_register_threshold_callback (called from

dm_pool_register_metadata_threshold).

Fix this by in dm_pool_register_metadata_threshold() by returning the

-EINVAL error if the thin-pool is in fail mode. Also fail pool_ctr()

with a new error message: "Error registering metadata threshold".

Fixes: ac8c3f3df65e4 ("dm thin: generate event when metadata threshold passed")

Cc: stable@vger.kernel.org

Reported-by: Hulk Robot <hulkci@huawei.com>

Signed-off-by: Luo Meng <luomeng12@huawei.com>

Signed-off-by: Mike Snitzer <snitzer@kernel.org>

Signed-off-by: Coly Li <colyli@suse.de>

---

 drivers/md/dm-thin-metadata.c | 7 +++++--

 drivers/md/dm-thin.c          | 4 +++-

 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c

index 2db7030aba00..a27395c8621f 100644

--- a/drivers/md/dm-thin-metadata.c

+++ b/drivers/md/dm-thin-metadata.c

@@ -2045,10 +2045,13 @@ int dm_pool_register_metadata_threshold(struct dm_pool_metadata *pmd,

 					dm_sm_threshold_fn fn,

 					void *context)

 {

-	int r;

+	int r = -EINVAL;

 	pmd_write_lock_in_core(pmd);

-	r = dm_sm_register_threshold_callback(pmd->metadata_sm, threshold, fn, context);

+	if (!pmd->fail_io) {

+		r = dm_sm_register_threshold_callback(pmd->metadata_sm,

+						      threshold, fn, context);

+	}

 	pmd_write_unlock(pmd);

 	return r;

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c

index 84c083f76673..e76c96c760a9 100644

--- a/drivers/md/dm-thin.c

+++ b/drivers/md/dm-thin.c

@@ -3375,8 +3375,10 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)

 						calc_metadata_threshold(pt),

 						metadata_low_callback,

 						pool);

-	if (r)

+	if (r) {

+		ti->error = "Error registering metadata threshold";

 		goto out_flags_changed;

+	}

 	dm_pool_register_pre_commit_callback(pool->pmd,

 					     metadata_pre_commit_callback, pool);

-- 

2.35.3