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authorAnatoliy Glagolev <glagolig@gmail.com>2018-06-13 15:38:51 -0600
committerJens Axboe <axboe@kernel.dk>2018-06-15 08:15:37 -0600
commitd6c73964f1e2a07f75057fb32ae46f6599036f93 (patch)
tree7e77c8a410880ad63db5b44303b7d6a3a472d95d /block/bsg.c
parentbe7f99c536c5aeebad29082b7d8dce32077fea14 (diff)
downloadlinux-stericsson-d6c73964f1e2a07f75057fb32ae46f6599036f93.tar.gz
bsg: fix race of bsg_open and bsg_unregister
The existing implementation allows races between bsg_unregister and bsg_open paths. bsg_unregister and request_queue cleanup and deletion may start and complete right after bsg_get_device (in bsg_open path) retrieves bsg_class_device and releases the mutex. Then bsg_open path touches freed memory of bsg_class_device and request_queue. One possible fix is to hold the mutex all the way through bsg_get_device instead of releasing it after bsg_class_device retrieval. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-Off-By: Anatoliy Glagolev <glagolig@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/bsg.c')
-rw-r--r--block/bsg.c22
1 files changed, 11 insertions, 11 deletions
diff --git a/block/bsg.c b/block/bsg.c
index 132e657e2d91..66602c489956 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -693,6 +693,8 @@ static struct bsg_device *bsg_add_device(struct inode *inode,
struct bsg_device *bd;
unsigned char buf[32];
+ lockdep_assert_held(&bsg_mutex);
+
if (!blk_get_queue(rq))
return ERR_PTR(-ENXIO);
@@ -707,14 +709,12 @@ static struct bsg_device *bsg_add_device(struct inode *inode,
bsg_set_block(bd, file);
atomic_set(&bd->ref_count, 1);
- mutex_lock(&bsg_mutex);
hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1);
bsg_dbg(bd, "bound to <%s>, max queue %d\n",
format_dev_t(buf, inode->i_rdev), bd->max_queue);
- mutex_unlock(&bsg_mutex);
return bd;
}
@@ -722,7 +722,7 @@ static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
{
struct bsg_device *bd;
- mutex_lock(&bsg_mutex);
+ lockdep_assert_held(&bsg_mutex);
hlist_for_each_entry(bd, bsg_dev_idx_hash(minor), dev_list) {
if (bd->queue == q) {
@@ -732,7 +732,6 @@ static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
}
bd = NULL;
found:
- mutex_unlock(&bsg_mutex);
return bd;
}
@@ -746,17 +745,18 @@ static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
*/
mutex_lock(&bsg_mutex);
bcd = idr_find(&bsg_minor_idr, iminor(inode));
- mutex_unlock(&bsg_mutex);
- if (!bcd)
- return ERR_PTR(-ENODEV);
+ if (!bcd) {
+ bd = ERR_PTR(-ENODEV);
+ goto out_unlock;
+ }
bd = __bsg_get_device(iminor(inode), bcd->queue);
- if (bd)
- return bd;
-
- bd = bsg_add_device(inode, bcd->queue, file);
+ if (!bd)
+ bd = bsg_add_device(inode, bcd->queue, file);
+out_unlock:
+ mutex_unlock(&bsg_mutex);
return bd;
}