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authorYufen Yu <yuyufen@huawei.com>2018-02-24 05:05:56 +0100
committerShaohua Li <sh.li@alibaba-inc.com>2018-02-25 19:44:39 +0100
commit3de59bb9d551428cbdc76a9ea57883f82e350b4d (patch)
treee52cf39c6f24c60dca270845a5163c37fa8f2009 /drivers/md
parentmd: fix a potential deadlock of raid5/raid10 reshape (diff)
downloadlinux-3de59bb9d551428cbdc76a9ea57883f82e350b4d.tar.xz
linux-3de59bb9d551428cbdc76a9ea57883f82e350b4d.zip
md/raid1: fix NULL pointer dereference
In handle_write_finished(), if r1_bio->bios[m] != NULL, it thinks the corresponding conf->mirrors[m].rdev is also not NULL. But, it is not always true. Even if some io hold replacement rdev(i.e. rdev->nr_pending.count > 0), raid1_remove_disk() can also set the rdev as NULL. That means, bios[m] != NULL, but mirrors[m].rdev is NULL, resulting in NULL pointer dereference in handle_write_finished and sync_request_write. This patch can fix BUGs as follows: BUG: unable to handle kernel NULL pointer dereference at 0000000000000140 IP: [<ffffffff815bbbbd>] raid1d+0x2bd/0xfc0 PGD 12ab52067 PUD 12f587067 PMD 0 Oops: 0000 [#1] SMP CPU: 1 PID: 2008 Comm: md3_raid1 Not tainted 4.1.44+ #130 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1.fc26 04/01/2014 Call Trace: ? schedule+0x37/0x90 ? prepare_to_wait_event+0x83/0xf0 md_thread+0x144/0x150 ? wake_atomic_t_function+0x70/0x70 ? md_start_sync+0xf0/0xf0 kthread+0xd8/0xf0 ? kthread_worker_fn+0x160/0x160 ret_from_fork+0x42/0x70 ? kthread_worker_fn+0x160/0x160 BUG: unable to handle kernel NULL pointer dereference at 00000000000000b8 IP: sync_request_write+0x9e/0x980 PGD 800000007c518067 P4D 800000007c518067 PUD 8002b067 PMD 0 Oops: 0000 [#1] SMP PTI CPU: 24 PID: 2549 Comm: md3_raid1 Not tainted 4.15.0+ #118 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1.fc26 04/01/2014 Call Trace: ? sched_clock+0x5/0x10 ? sched_clock_cpu+0xc/0xb0 ? flush_pending_writes+0x3a/0xd0 ? pick_next_task_fair+0x4d5/0x5f0 ? __switch_to+0xa2/0x430 raid1d+0x65a/0x870 ? find_pers+0x70/0x70 ? find_pers+0x70/0x70 ? md_thread+0x11c/0x160 md_thread+0x11c/0x160 ? finish_wait+0x80/0x80 kthread+0x111/0x130 ? kthread_create_worker_on_cpu+0x70/0x70 ? do_syscall_64+0x6f/0x190 ? SyS_exit_group+0x10/0x10 ret_from_fork+0x35/0x40 Reviewed-by: NeilBrown <neilb@suse.com> Signed-off-by: Yufen Yu <yuyufen@huawei.com> Signed-off-by: Shaohua Li <sh.li@alibaba-inc.com>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/raid1.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index f978eddc7a21..fe872dc6712e 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1809,6 +1809,17 @@ static int raid1_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
struct md_rdev *repl =
conf->mirrors[conf->raid_disks + number].rdev;
freeze_array(conf, 0);
+ if (atomic_read(&repl->nr_pending)) {
+ /* It means that some queued IO of retry_list
+ * hold repl. Thus, we cannot set replacement
+ * as NULL, avoiding rdev NULL pointer
+ * dereference in sync_request_write and
+ * handle_write_finished.
+ */
+ err = -EBUSY;
+ unfreeze_array(conf);
+ goto abort;
+ }
clear_bit(Replacement, &repl->flags);
p->rdev = repl;
conf->mirrors[conf->raid_disks + number].rdev = NULL;