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md: add mddev->pers to avoid potential NULL pointer dereference 

When doing re-add, we need to ensure rdev->mddev->pers is not NULL,
which can avoid potential NULL pointer derefence in fallowing
add_bound_rdev().

Fixes: a6da4ef85c ("md: re-add a failed disk")
Cc: Xiao Ni <xni@redhat.com>
Cc: NeilBrown <neilb@suse.com>
Cc: <stable@vger.kernel.org> # 4.4+
Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: Yufen Yu <yuyufen@huawei.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
This commit is contained in:
Yufen Yu 2019-04-02 14:22:14 +08:00 committed by Song Liu
parent 0d413829bd
commit ee37e62191
1 changed files with 4 additions and 2 deletions
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6
drivers/md/md.c
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@ -2850,8 +2850,10 @@ state_store(struct md_rdev *rdev, const char *buf, size_t len)
err = 0;
}
} else if (cmd_match(buf, "re-add")) {
if (test_bit(Faulty, &rdev->flags) && (rdev->raid_disk == -1) &&
rdev->saved_raid_disk >= 0) {
if (!rdev->mddev->pers)
err = -EINVAL;
else if (test_bit(Faulty, &rdev->flags) && (rdev->raid_disk == -1) &&
rdev->saved_raid_disk >= 0) {
/* clear_bit is performed _after_ all the devices
* have their local Faulty bit cleared. If any writes
* happen in the meantime in the local node, they