在 2023/5/27 5:38, Song Liu 写道:
On Fri, May 26, 2023 at 12:47 AM <linan666@xxxxxxxxxxxxxxx> wrote:From: Li Nan <linan122@xxxxxxxxxx> need_replace will be set to 1 if no-Faulty mreplace exists, and mreplace will be deref later. However, the latter check of mreplace might set mreplace to NULL, null-ptr-deref occurs if need_replace is 1 at this time. Fix it by merging two checks into one. And replace 'need_replace' with 'mreplace' because their values are always the same. Fixes: ee37d7314a32 ("md/raid10: Fix raid10 replace hang when new added disk faulty") Signed-off-by: Li Nan <linan122@xxxxxxxxxx> --- drivers/md/raid10.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-) diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index 4fcfcb350d2b..e21502c03b45 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -3438,7 +3438,6 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr, int must_sync; int any_working; int need_recover = 0; - int need_replace = 0; struct raid10_info *mirror = &conf->mirrors[i]; struct md_rdev *mrdev, *mreplace; @@ -3451,10 +3450,10 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr, !test_bit(In_sync, &mrdev->flags)) need_recover = 1; if (mreplace != NULL && - !test_bit(Faulty, &mreplace->flags)) - need_replace = 1; + test_bit(Faulty, &mreplace->flags)) + mreplace = NULL; - if (!need_recover && !need_replace) { + if (!need_recover && !mreplace) { rcu_read_unlock(); continue; } @@ -3470,8 +3469,6 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr, rcu_read_unlock(); continue; }To make sure I understand the issue correctly: The null-ptr-deref only happens when the Faulty bit was set after the last check and before this check below, right?
Yes. I will improve log in next version. -- Thanks, Nan
