diff options
| author | Yu Kuai <yukuai3@huawei.com> | 2023-03-08 10:32:08 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2023-03-08 07:34:50 -0700 |
| commit | e2f2a39452c43b64ea3191642a2661cb8d03827a (patch) | |
| tree | bb85a3d9c05661e2c356f44fa95b0da4e059064d | |
| parent | e33062213ff2f9151e0d125e1c00f524c2b7acfe (diff) | |
block, bfq: fix uaf for 'stable_merge_bfqq'
Before commit fd571df0ac5b ("block, bfq: turn bfqq_data into an array
in bfq_io_cq"), process reference is read before bfq_put_stable_ref(),
and it's safe if bfq_put_stable_ref() put the last reference, because
process reference will be 0 and 'stable_merge_bfqq' won't be accessed
in this case. However, the commit changed the order and will cause
uaf for 'stable_merge_bfqq'.
In order to emphasize that bfq_put_stable_ref() can drop the last
reference, fix the problem by moving bfq_put_stable_ref() to the end of
bfq_setup_stable_merge().
Fixes: fd571df0ac5b ("block, bfq: turn bfqq_data into an array in bfq_io_cq")
Reported-and-tested-by: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Link: https://lore.kernel.org/linux-block/20230307071448.rzihxbm4jhbf5krj@shindev/
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | block/bfq-iosched.c | 18 |
1 files changed, 9 insertions, 9 deletions
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 8a8d4441519c..d9ed3108c17a 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -2854,11 +2854,11 @@ bfq_setup_stable_merge(struct bfq_data *bfqd, struct bfq_queue *bfqq, { int proc_ref = min(bfqq_process_refs(bfqq), bfqq_process_refs(stable_merge_bfqq)); - struct bfq_queue *new_bfqq; + struct bfq_queue *new_bfqq = NULL; - if (idling_boosts_thr_without_issues(bfqd, bfqq) || - proc_ref == 0) - return NULL; + bfqq_data->stable_merge_bfqq = NULL; + if (idling_boosts_thr_without_issues(bfqd, bfqq) || proc_ref == 0) + goto out; /* next function will take at least one ref */ new_bfqq = bfq_setup_merge(bfqq, stable_merge_bfqq); @@ -2873,6 +2873,11 @@ bfq_setup_stable_merge(struct bfq_data *bfqd, struct bfq_queue *bfqq, new_bfqq_data->stably_merged = true; } } + +out: + /* deschedule stable merge, because done or aborted here */ + bfq_put_stable_ref(stable_merge_bfqq); + return new_bfqq; } @@ -2933,11 +2938,6 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq, struct bfq_queue *stable_merge_bfqq = bfqq_data->stable_merge_bfqq; - /* deschedule stable merge, because done or aborted here */ - bfq_put_stable_ref(stable_merge_bfqq); - - bfqq_data->stable_merge_bfqq = NULL; - return bfq_setup_stable_merge(bfqd, bfqq, stable_merge_bfqq, bfqq_data); |