Re: [PATCH v2 1/4] md/raid10: fix null-ptr-deref of mreplace in raid10_sync_request

From: Li Nan
Date: Fri May 26 2023 - 21:30:04 EST

在 2023/5/27 9:21, Yu Kuai 写道:

在 2023/05/26 15:45, linan666@xxxxxxxxxxxxxxx 写道:
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>

Other than some nits below, this patch looks good to me, feel free too

Reviewed-by: Yu Kuai <yukuai3@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))
This can be keeped in one line.

OK, I will change it.
Thanks for your review.