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Message-Id: <20251030062807.1515356-3-linan666@huaweicloud.com>
Date: Thu, 30 Oct 2025 14:28:05 +0800
From: linan666@...weicloud.com
To: corbet@....net,
song@...nel.org,
yukuai@...as.com,
linan122@...wei.com,
hare@...e.de,
xni@...hat.com
Cc: linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-raid@...r.kernel.org,
linan666@...weicloud.com,
yangerkun@...wei.com,
yi.zhang@...wei.com
Subject: [PATCH v8 2/4] md: init bioset in mddev_init
From: Li Nan <linan122@...wei.com>
IO operations may be needed before md_run(), such as updating metadata
after writing sysfs. Without bioset, this triggers a NULL pointer
dereference as below:
BUG: kernel NULL pointer dereference, address: 0000000000000020
Call Trace:
md_update_sb+0x658/0xe00
new_level_store+0xc5/0x120
md_attr_store+0xc9/0x1e0
sysfs_kf_write+0x6f/0xa0
kernfs_fop_write_iter+0x141/0x2a0
vfs_write+0x1fc/0x5a0
ksys_write+0x79/0x180
__x64_sys_write+0x1d/0x30
x64_sys_call+0x2818/0x2880
do_syscall_64+0xa9/0x580
entry_SYSCALL_64_after_hwframe+0x4b/0x53
Reproducer
```
mdadm -CR /dev/md0 -l1 -n2 /dev/sd[cd]
echo inactive > /sys/block/md0/md/array_state
echo 10 > /sys/block/md0/md/new_level
```
mddev_init() can only be called once per mddev, no need to test if bioset
has been initialized anymore.
Fixes: d981ed841930 ("md: Add new_level sysfs interface")
Signed-off-by: Li Nan <linan122@...wei.com>
---
drivers/md/md.c | 69 +++++++++++++++++++++++--------------------------
1 file changed, 33 insertions(+), 36 deletions(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index f6fd55a1637b..dffc6a482181 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -730,6 +730,8 @@ static void mddev_clear_bitmap_ops(struct mddev *mddev)
int mddev_init(struct mddev *mddev)
{
+ int err = 0;
+
if (!IS_ENABLED(CONFIG_MD_BITMAP))
mddev->bitmap_id = ID_BITMAP_NONE;
else
@@ -741,10 +743,23 @@ int mddev_init(struct mddev *mddev)
if (percpu_ref_init(&mddev->writes_pending, no_op,
PERCPU_REF_ALLOW_REINIT, GFP_KERNEL)) {
- percpu_ref_exit(&mddev->active_io);
- return -ENOMEM;
+ err = -ENOMEM;
+ goto exit_acitve_io;
}
+ err = bioset_init(&mddev->bio_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
+ if (err)
+ goto exit_writes_pending;
+
+ err = bioset_init(&mddev->sync_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
+ if (err)
+ goto exit_bio_set;
+
+ err = bioset_init(&mddev->io_clone_set, BIO_POOL_SIZE,
+ offsetof(struct md_io_clone, bio_clone), 0);
+ if (err)
+ goto exit_sync_set;
+
/* We want to start with the refcount at zero */
percpu_ref_put(&mddev->writes_pending);
@@ -773,11 +788,24 @@ int mddev_init(struct mddev *mddev)
INIT_WORK(&mddev->del_work, mddev_delayed_delete);
return 0;
+
+exit_sync_set:
+ bioset_exit(&mddev->sync_set);
+exit_bio_set:
+ bioset_exit(&mddev->bio_set);
+exit_writes_pending:
+ percpu_ref_exit(&mddev->writes_pending);
+exit_acitve_io:
+ percpu_ref_exit(&mddev->active_io);
+ return err;
}
EXPORT_SYMBOL_GPL(mddev_init);
void mddev_destroy(struct mddev *mddev)
{
+ bioset_exit(&mddev->bio_set);
+ bioset_exit(&mddev->sync_set);
+ bioset_exit(&mddev->io_clone_set);
percpu_ref_exit(&mddev->active_io);
percpu_ref_exit(&mddev->writes_pending);
}
@@ -6393,29 +6421,9 @@ int md_run(struct mddev *mddev)
nowait = nowait && bdev_nowait(rdev->bdev);
}
- if (!bioset_initialized(&mddev->bio_set)) {
- err = bioset_init(&mddev->bio_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
- if (err)
- return err;
- }
- if (!bioset_initialized(&mddev->sync_set)) {
- err = bioset_init(&mddev->sync_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
- if (err)
- goto exit_bio_set;
- }
-
- if (!bioset_initialized(&mddev->io_clone_set)) {
- err = bioset_init(&mddev->io_clone_set, BIO_POOL_SIZE,
- offsetof(struct md_io_clone, bio_clone), 0);
- if (err)
- goto exit_sync_set;
- }
-
pers = get_pers(mddev->level, mddev->clevel);
- if (!pers) {
- err = -EINVAL;
- goto abort;
- }
+ if (!pers)
+ return -EINVAL;
if (mddev->level != pers->head.id) {
mddev->level = pers->head.id;
mddev->new_level = pers->head.id;
@@ -6426,8 +6434,7 @@ int md_run(struct mddev *mddev)
pers->start_reshape == NULL) {
/* This personality cannot handle reshaping... */
put_pers(pers);
- err = -EINVAL;
- goto abort;
+ return -EINVAL;
}
if (pers->sync_request) {
@@ -6554,12 +6561,6 @@ int md_run(struct mddev *mddev)
mddev->private = NULL;
put_pers(pers);
md_bitmap_destroy(mddev);
-abort:
- bioset_exit(&mddev->io_clone_set);
-exit_sync_set:
- bioset_exit(&mddev->sync_set);
-exit_bio_set:
- bioset_exit(&mddev->bio_set);
return err;
}
EXPORT_SYMBOL_GPL(md_run);
@@ -6784,10 +6785,6 @@ static void __md_stop(struct mddev *mddev)
mddev->private = NULL;
put_pers(pers);
clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
-
- bioset_exit(&mddev->bio_set);
- bioset_exit(&mddev->sync_set);
- bioset_exit(&mddev->io_clone_set);
}
void md_stop(struct mddev *mddev)
--
2.39.2
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