[PATCH 6.4 036/800] md/raid10: fix null-ptr-deref of mreplace in raid10_sync_request

Greg Kroah-Hartman
2023-07-16T19:54:29Z

From: Li Nan <linan122@huawei.com>

[ Upstream commit 34817a2441747b48e444cb0e05d84e14bc9443da ]

There are two check of 'mreplace' in raid10_sync_request(). In the first
check, 'need_replace' will be set and 'mreplace' will be used later if
no-Faulty 'mreplace' exists, In the second check, 'mreplace' will be
set to NULL if it is Faulty, but 'need_replace' will not be changed
accordingly. null-ptr-deref occurs if Faulty is set between two check.

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@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230527072218.2365857-2-linan666@huaweicloud.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/md/raid10.c | 14 +++++---------
1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 4fcfcb350d2b4..0acb4c103c10e 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;

@@ -3450,11 +3449,10 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
!test_bit(Faulty, &mrdev->flags) &&
!test_bit(In_sync, &mrdev->flags))
need_recover = 1;
- if (mreplace != NULL &&
- !test_bit(Faulty, &mreplace->flags))
- need_replace = 1;
+ if (mreplace && test_bit(Faulty, &mreplace->flags))
+ mreplace = NULL;

- if (!need_recover && !need_replace) {
+ if (!need_recover && !mreplace) {
rcu_read_unlock();
continue;
}
@@ -3470,8 +3468,6 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
rcu_read_unlock();
continue;
}
- if (mreplace && test_bit(Faulty, &mreplace->flags))
- mreplace = NULL;
/* Unless we are doing a full sync, or a replacement
* we only need to recover the block if it is set in
* the bitmap
@@ -3594,11 +3590,11 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
bio = r10_bio->devs[1].repl_bio;
if (bio)
bio->bi_end_io = NULL;
- /* Note: if need_replace, then bio
+ /* Note: if replace is not NULL, then bio
* cannot be NULL as r10buf_pool_alloc will
* have allocated it.
*/
- if (!need_replace)
+ if (!mreplace)
break;
bio->bi_next = biolist;
biolist = bio;
--
2.39.2