[PATCH 5.10 18/63] io_uring: use bottom half safe lock for fixed file data

[Greg Kroah-Hartman]

From: Jens Axboe <ax...@kernel.dk>

commit ac0648a56c1ff66c1cbf735075ad33a26cbc50de upstream.

io_file_data_ref_zero() can be invoked from soft-irq from the RCU core,
hence we need to ensure that the file_data lock is bottom half safe. Use
the _bh() variants when grabbing this lock.

Reported-by: syzbot+1f4ba1e5520762c52...@syzkaller.appspotmail.com
Signed-off-by: Jens Axboe <ax...@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 fs/io_uring.c |   16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -7000,9 +7000,9 @@ static int io_sqe_files_unregister(struc
        if (!data)
                return -ENXIO;
 
-       spin_lock(&data->lock);
+       spin_lock_bh(&data->lock);
        ref_node = data->node;
-       spin_unlock(&data->lock);
+       spin_unlock_bh(&data->lock);
        if (ref_node)
                percpu_ref_kill(&ref_node->refs);
 
@@ -7385,7 +7385,7 @@ static void io_file_data_ref_zero(struct
        data = ref_node->file_data;
        ctx = data->ctx;
 
-       spin_lock(&data->lock);
+       spin_lock_bh(&data->lock);
        ref_node->done = true;
 
        while (!list_empty(&data->ref_list)) {
@@ -7397,7 +7397,7 @@ static void io_file_data_ref_zero(struct
                list_del(&ref_node->node);
                first_add |= llist_add(&ref_node->llist, &ctx->file_put_llist);
        }
-       spin_unlock(&data->lock);
+       spin_unlock_bh(&data->lock);
 
        if (percpu_ref_is_dying(&data->refs))
                delay = 0;
@@ -7520,9 +7520,9 @@ static int io_sqe_files_register(struct
        }
 
        file_data->node = ref_node;
-       spin_lock(&file_data->lock);
+       spin_lock_bh(&file_data->lock);
        list_add_tail(&ref_node->node, &file_data->ref_list);
-       spin_unlock(&file_data->lock);
+       spin_unlock_bh(&file_data->lock);
        percpu_ref_get(&file_data->refs);
        return ret;
 out_fput:
@@ -7679,10 +7679,10 @@ static int __io_sqe_files_update(struct
 
        if (needs_switch) {
                percpu_ref_kill(&data->node->refs);
-               spin_lock(&data->lock);
+               spin_lock_bh(&data->lock);
                list_add_tail(&ref_node->node, &data->ref_list);
                data->node = ref_node;
-               spin_unlock(&data->lock);
+               spin_unlock_bh(&data->lock);
                percpu_ref_get(&ctx->file_data->refs);
        } else
                destroy_fixed_file_ref_node(ref_node);