[PATCH AUTOSEL 6.6 29/40] nbd: pass nbd_sock to nbd_read_reply() instead of index

Sasha Levin
2023-11-28T21:13:08Z

From: Li Nan <linan122@huawei.com>

[ Upstream commit 98c598afc22d4e43c2ad91860b65996d0c099a5d ]

If a socket is processing ioctl 'NBD_SET_SOCK', config->socks might be
krealloc in nbd_add_socket(), and a garbage request is received now, a UAF
may occurs.

T1
nbd_ioctl
__nbd_ioctl
nbd_add_socket
blk_mq_freeze_queue
T2
recv_work
nbd_read_reply
sock_xmit
krealloc config->socks
def config->socks

Pass nbd_sock to nbd_read_reply(). And introduce a new function
sock_xmit_recv(), which differs from sock_xmit only in the way it get
socket.

==================================================================
BUG: KASAN: use-after-free in sock_xmit+0x525/0x550
Read of size 8 at addr ffff8880188ec428 by task kworker/u12:1/18779

Workqueue: knbd4-recv recv_work
Call Trace:
__dump_stack
dump_stack+0xbe/0xfd
print_address_description.constprop.0+0x19/0x170
__kasan_report.cold+0x6c/0x84
kasan_report+0x3a/0x50
sock_xmit+0x525/0x550
nbd_read_reply+0xfe/0x2c0
recv_work+0x1c2/0x750
process_one_work+0x6b6/0xf10
worker_thread+0xdd/0xd80
kthread+0x30a/0x410
ret_from_fork+0x22/0x30

Allocated by task 18784:
kasan_save_stack+0x1b/0x40
kasan_set_track
set_alloc_info
__kasan_kmalloc
__kasan_kmalloc.constprop.0+0xf0/0x130
slab_post_alloc_hook
slab_alloc_node
slab_alloc
__kmalloc_track_caller+0x157/0x550
__do_krealloc
krealloc+0x37/0xb0
nbd_add_socket
+0x2d3/0x880
__nbd_ioctl
nbd_ioctl+0x584/0x8e0
__blkdev_driver_ioctl
blkdev_ioctl+0x2a0/0x6e0
block_ioctl+0xee/0x130
vfs_ioctl
__do_sys_ioctl
__se_sys_ioctl+0x138/0x190
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x61/0xc6

Freed by task 18784:
kasan_save_stack+0x1b/0x40
kasan_set_track+0x1c/0x30
kasan_set_free_info+0x20/0x40
__kasan_slab_free.part.0+0x13f/0x1b0
slab_free_hook
slab_free_freelist_hook
slab_free
kfree+0xcb/0x6c0
krealloc+0x56/0xb0
nbd_add_socket+0x2d3/0x880
__nbd_ioctl
nbd_ioctl+0x584/0x8e0
__blkdev_driver_ioctl
blkdev_ioctl+0x2a0/0x6e0
block_ioctl+0xee/0x130
vfs_ioctl
__do_sys_ioctl
__se_sys_ioctl+0x138/0x190
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x61/0xc6

Signed-off-by: Li Nan <linan122@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20230911023308.3467802-1-linan666@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/block/nbd.c | 35 ++++++++++++++++++++++-------------
1 file changed, 22 insertions(+), 13 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 3f03cb3dc33cc..b6414e1e645b7 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -67,6 +67,7 @@ struct nbd_sock {
struct recv_thread_args {
struct work_struct work;
struct nbd_device *nbd;
+ struct nbd_sock *nsock;
int index;
};

@@ -505,15 +506,9 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req)
return BLK_EH_DONE;
}

-/*
- * Send or receive packet. Return a positive value on success and
- * negtive value on failue, and never return 0.
- */
-static int sock_xmit(struct nbd_device *nbd, int index, int send,
- struct iov_iter *iter, int msg_flags, int *sent)
+static int __sock_xmit(struct nbd_device *nbd, struct socket *sock, int send,
+ struct iov_iter *iter, int msg_flags, int *sent)
{
- struct nbd_config *config = nbd->config;
- struct socket *sock = config->socks[index]->sock;
int result;
struct msghdr msg;
unsigned int noreclaim_flag;
@@ -556,6 +551,19 @@ static int sock_xmit(struct nbd_device *nbd, int index, int send,
return result;
}

+/*
+ * Send or receive packet. Return a positive value on success and
+ * negtive value on failure, and never return 0.
+ */
+static int sock_xmit(struct nbd_device *nbd, int index, int send,
+ struct iov_iter *iter, int msg_flags, int *sent)
+{
+ struct nbd_config *config = nbd->config;
+ struct socket *sock = config->socks[index]->sock;
+
+ return __sock_xmit(nbd, sock, send, iter, msg_flags, sent);
+}
+
/*
* Different settings for sk->sk_sndtimeo can result in different return values
* if there is a signal pending when we enter sendmsg, because reasons?
@@ -712,7 +720,7 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
return 0;
}

-static int nbd_read_reply(struct nbd_device *nbd, int index,
+static int nbd_read_reply(struct nbd_device *nbd, struct socket *sock,
struct nbd_reply *reply)
{
struct kvec iov = {.iov_base = reply, .iov_len = sizeof(*reply)};
@@ -721,7 +729,7 @@ static int nbd_read_reply(struct nbd_device *nbd, int index,

reply->magic = 0;
iov_iter_kvec(&to, ITER_DEST, &iov, 1, sizeof(*reply));
- result = sock_xmit(nbd, index, 0, &to, MSG_WAITALL, NULL);
+ result = __sock_xmit(nbd, sock, 0, &to, MSG_WAITALL, NULL);
if (result < 0) {
if (!nbd_disconnected(nbd->config))
dev_err(disk_to_dev(nbd->disk),
@@ -845,14 +853,14 @@ static void recv_work(struct work_struct *work)
struct nbd_device *nbd = args->nbd;
struct nbd_config *config = nbd->config;
struct request_queue *q = nbd->disk->queue;
- struct nbd_sock *nsock;
+ struct nbd_sock *nsock = args->nsock;
struct nbd_cmd *cmd;
struct request *rq;

while (1) {
struct nbd_reply reply;

- if (nbd_read_reply(nbd, args->index, &reply))
+ if (nbd_read_reply(nbd, nsock->sock, &reply))
break;

/*
@@ -887,7 +895,6 @@ static void recv_work(struct work_struct *work)
percpu_ref_put(&q->q_usage_counter);
}

- nsock = config->socks[args->index];
mutex_lock(&nsock->tx_lock);
nbd_mark_nsock_dead(nbd, nsock, 1);
mutex_unlock(&nsock->tx_lock);
@@ -1231,6 +1238,7 @@ static int nbd_reconnect_socket(struct nbd_device *nbd, unsigned long arg)
INIT_WORK(&args->work, recv_work);
args->index = i;
args->nbd = nbd;
+ args->nsock = nsock;
nsock->cookie++;
mutex_unlock(&nsock->tx_lock);
sockfd_put(old);
@@ -1413,6 +1421,7 @@ static int nbd_start_device(struct nbd_device *nbd)
refcount_inc(&nbd->config_refs);
INIT_WORK(&args->work, recv_work);
args->nbd = nbd;
+ args->nsock = config->socks[i];
args->index = i;
queue_work(nbd->recv_workq, &args->work);
}
--
2.42.0