From 428913bce1e67ccb4dae317fd0332545bf8c9233 Mon Sep 17 00:00:00 2001 From: Yu Kuai Date: Tue, 7 Mar 2023 18:55:52 +0800 Subject: block: fix wrong mode for blkdev_put() from disk_scan_partitions() If disk_scan_partitions() is called with 'FMODE_EXCL', blkdev_get_by_dev() will be called without 'FMODE_EXCL', however, follow blkdev_put() is still called with 'FMODE_EXCL', which will cause 'bd_holders' counter to leak. Fix the problem by using the right mode for blkdev_put(). Reported-by: syzbot+2bcc0d79e548c4f62a59@syzkaller.appspotmail.com Link: https://lore.kernel.org/lkml/f9649d501bc8c3444769418f6c26263555d9d3be.camel@linux.ibm.com/T/ Tested-by: Julian Ruess Fixes: e5cfefa97bcc ("block: fix scan partition for exclusively open device again") Signed-off-by: Yu Kuai Reviewed-by: Jan Kara Signed-off-by: Jens Axboe --- block/genhd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/genhd.c b/block/genhd.c index 3ee5577e1586..02d9cfb9e077 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -385,7 +385,7 @@ int disk_scan_partitions(struct gendisk *disk, fmode_t mode) if (IS_ERR(bdev)) ret = PTR_ERR(bdev); else - blkdev_put(bdev, mode); + blkdev_put(bdev, mode & ~FMODE_EXCL); if (!(mode & FMODE_EXCL)) bd_abort_claiming(disk->part0, disk_scan_partitions); -- cgit v1.2.3 From e33062213ff2f9151e0d125e1c00f524c2b7acfe Mon Sep 17 00:00:00 2001 From: Sagi Grimberg Date: Fri, 3 Mar 2023 10:43:23 +0200 Subject: docs: sysfs-block: document hidden sysfs entry /sys/block//hidden is undocumented. Document it. Signed-off-by: Sagi Grimberg Reviewed-by: Chaitanya Kulkarni Link: https://lore.kernel.org/r/20230303084323.228098-1-sagi@grimberg.me Signed-off-by: Jens Axboe --- Documentation/ABI/stable/sysfs-block | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/Documentation/ABI/stable/sysfs-block b/Documentation/ABI/stable/sysfs-block index ac1e519272aa..282de3680367 100644 --- a/Documentation/ABI/stable/sysfs-block +++ b/Documentation/ABI/stable/sysfs-block @@ -705,6 +705,15 @@ Description: zoned will report "none". +What: /sys/block//hidden +Date: March 2023 +Contact: linux-block@vger.kernel.org +Description: + [RO] the block device is hidden. it doesn’t produce events, and + can’t be opened from userspace or using blkdev_get*. + Used for the underlying components of multipath devices. + + What: /sys/block//stat Date: February 2008 Contact: Jerome Marchand -- cgit v1.2.3 From e2f2a39452c43b64ea3191642a2661cb8d03827a Mon Sep 17 00:00:00 2001 From: Yu Kuai Date: Wed, 8 Mar 2023 10:32:08 +0800 Subject: 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 Link: https://lore.kernel.org/linux-block/20230307071448.rzihxbm4jhbf5krj@shindev/ Signed-off-by: Yu Kuai Reviewed-by: Jan Kara Signed-off-by: Jens Axboe --- block/bfq-iosched.c | 18 +++++++++--------- 1 file 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); -- cgit v1.2.3