[PATCH v2 5/7] bfq: fix potential kernel crash when print dev err info
From: Yufen Yu <hidden>
Date: 2020-02-26 11:11:52
Also in:
linux-fsdevel
Subsystem:
bfq i/o scheduler, block layer, the rest · Maintainers:
Yu Kuai, Jens Axboe, Linus Torvalds
We use bdi_get_dev_name() to get device name, avoiding use-after-free or NULL pointer reference for ->dev. Signed-off-by: Yufen Yu <redacted> --- block/bfq-iosched.c | 7 +++++-- include/linux/backing-dev.h | 2 ++ 2 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 00904611b8e4..8d41783d8e77 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c@@ -123,6 +123,7 @@ #include <linux/ioprio.h> #include <linux/sbitmap.h> #include <linux/delay.h> +#include <linux/backing-dev.h> #include "blk.h" #include "blk-mq.h"
@@ -4971,6 +4972,7 @@ bfq_set_next_ioprio_data(struct bfq_queue *bfqq, struct bfq_io_cq *bic) struct task_struct *tsk = current; int ioprio_class; struct bfq_data *bfqd = bfqq->bfqd; + char dname[BDI_DEV_NAME_LEN]; if (!bfqd) return;
@@ -4978,8 +4980,9 @@ bfq_set_next_ioprio_data(struct bfq_queue *bfqq, struct bfq_io_cq *bic) ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio); switch (ioprio_class) { default: - dev_err(&bfqq->bfqd->queue->backing_dev_info->rcu_dev->dev, - "bfq: bad prio class %d\n", ioprio_class); + bdi_get_dev_name(bfqq->bfqd->queue->backing_dev_info, + dname, BDI_DEV_NAME_LEN); + pr_err("bdi %s: bfq: bad prio class %d\n", dname, ioprio_class); /* fall through */ case IOPRIO_CLASS_NONE: /*
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 89d1cb7923f5..291db069f7da 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h@@ -19,6 +19,8 @@ #include <linux/backing-dev-defs.h> #include <linux/slab.h> +#define BDI_DEV_NAME_LEN 32 + static inline struct backing_dev_info *bdi_get(struct backing_dev_info *bdi) { kref_get(&bdi->refcnt);
--
2.16.2.dirty