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Date: Thu, 18 Jan 2024 09:20:09 +0800
From: shaozhengchao <shaozhengchao@...wei.com>
To: <linux-kernel@...r.kernel.org>, <netdev@...r.kernel.org>
CC: <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
<pabeni@...hat.com>, <brauner@...nel.org>, <dchinner@...hat.com>,
<jlayton@...nel.org>, <jack@...e.cz>, <riel@...riel.com>,
<weiyongjun1@...wei.com>, <yuehaibing@...wei.com>
Subject: Re: [PATCH v2] ipc/mqueue: fix potential sleeping issue in
mqueue_flush_file
++ping
Does anyone have ideas with this patch?
On 2024/1/2 9:09, shaozhengchao wrote:
> +ping
>
> Does anyone have ideas with this patch?
>
> On 2023/12/20 10:12, Zhengchao Shao wrote:
>> I analyze the potential sleeping issue of the following processes:
>> Thread A Thread B
>> ... netlink_create //ref = 1
>> do_mq_notify ...
>> sock = netlink_getsockbyfilp ... //ref = 2
>> info->notify_sock = sock; ...
>> ... netlink_sendmsg
>> ... skb =
>> netlink_alloc_large_skb //skb->head is vmalloced
>> ... netlink_unicast
>> ... sk =
>> netlink_getsockbyportid //ref = 3
>> ... netlink_sendskb
>> ... __netlink_sendskb
>> ... skb_queue_tail //put
>> skb to sk_receive_queue
>> ... sock_put //ref = 2
>> ... ...
>> ... netlink_release
>> ... deferred_put_nlk_sk //ref = 1
>> mqueue_flush_file
>> spin_lock
>> remove_notification
>> netlink_sendskb
>> sock_put //ref = 0
>> sk_free
>> ...
>> __sk_destruct
>> netlink_sock_destruct
>> skb_queue_purge //get skb from sk_receive_queue
>> ...
>> __skb_queue_purge_reason
>> kfree_skb_reason
>> __kfree_skb
>> ...
>> skb_release_all
>> skb_release_head_state
>> netlink_skb_destructor
>> vfree(skb->head) //sleeping while holding
>> spinlock
>>
>> In netlink_sendmsg, if the memory pointed to by skb->head is allocated by
>> vmalloc, and is put to sk_receive_queue queue, also the skb is not freed.
>> When the mqueue executes flush, the sleeping bug will occur. Use mutex
>> lock instead of spin lock in mqueue_flush_file.
>>
>> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
>> Signed-off-by: Zhengchao Shao <shaozhengchao@...wei.com>
>> ---
>> v2: CCed some networking maintainer & netdev list
>> ---
>> ipc/mqueue.c | 48 ++++++++++++++++++++++++------------------------
>> 1 file changed, 24 insertions(+), 24 deletions(-)
>>
>> diff --git a/ipc/mqueue.c b/ipc/mqueue.c
>> index 5eea4dc0509e..f6f92e3f82e4 100644
>> --- a/ipc/mqueue.c
>> +++ b/ipc/mqueue.c
>> @@ -118,9 +118,9 @@ struct posix_msg_tree_node {
>> * Solution: use _release and _acquire barriers.
>> *
>> * 3) There is intentionally no barrier when setting current->state
>> - * to TASK_INTERRUPTIBLE: spin_unlock(&info->lock) provides the
>> + * to TASK_INTERRUPTIBLE: mutex_unlock(&info->lock) provides the
>> * release memory barrier, and the wakeup is triggered when holding
>> - * info->lock, i.e. spin_lock(&info->lock) provided a pairing
>> + * info->lock, i.e. mutex_lock(&info->lock) provided a pairing
>> * acquire memory barrier.
>> */
>> @@ -132,7 +132,7 @@ struct ext_wait_queue { /* queue of
>> sleeping tasks */
>> };
>> struct mqueue_inode_info {
>> - spinlock_t lock;
>> + struct mutex lock;
>> struct inode vfs_inode;
>> wait_queue_head_t wait_q;
>> @@ -312,7 +312,7 @@ static struct inode *mqueue_get_inode(struct
>> super_block *sb,
>> inode->i_size = FILENT_SIZE;
>> /* mqueue specific info */
>> info = MQUEUE_I(inode);
>> - spin_lock_init(&info->lock);
>> + mutex_init(&info->lock);
>> init_waitqueue_head(&info->wait_q);
>> INIT_LIST_HEAD(&info->e_wait_q[0].list);
>> INIT_LIST_HEAD(&info->e_wait_q[1].list);
>> @@ -523,11 +523,11 @@ static void mqueue_evict_inode(struct inode *inode)
>> ipc_ns = get_ns_from_inode(inode);
>> info = MQUEUE_I(inode);
>> - spin_lock(&info->lock);
>> + mutex_lock(&info->lock);
>> while ((msg = msg_get(info)) != NULL)
>> list_add_tail(&msg->m_list, &tmp_msg);
>> kfree(info->node_cache);
>> - spin_unlock(&info->lock);
>> + mutex_unlock(&info->lock);
>> list_for_each_entry_safe(msg, nmsg, &tmp_msg, m_list) {
>> list_del(&msg->m_list);
>> @@ -640,7 +640,7 @@ static ssize_t mqueue_read_file(struct file *filp,
>> char __user *u_data,
>> char buffer[FILENT_SIZE];
>> ssize_t ret;
>> - spin_lock(&info->lock);
>> + mutex_lock(&info->lock);
>> snprintf(buffer, sizeof(buffer),
>> "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
>> info->qsize,
>> @@ -649,7 +649,7 @@ static ssize_t mqueue_read_file(struct file *filp,
>> char __user *u_data,
>> info->notify.sigev_notify == SIGEV_SIGNAL) ?
>> info->notify.sigev_signo : 0,
>> pid_vnr(info->notify_owner));
>> - spin_unlock(&info->lock);
>> + mutex_unlock(&info->lock);
>> buffer[sizeof(buffer)-1] = '\0';
>> ret = simple_read_from_buffer(u_data, count, off, buffer,
>> @@ -665,11 +665,11 @@ static int mqueue_flush_file(struct file *filp,
>> fl_owner_t id)
>> {
>> struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
>> - spin_lock(&info->lock);
>> + mutex_lock(&info->lock);
>> if (task_tgid(current) == info->notify_owner)
>> remove_notification(info);
>> - spin_unlock(&info->lock);
>> + mutex_unlock(&info->lock);
>> return 0;
>> }
>> @@ -680,13 +680,13 @@ static __poll_t mqueue_poll_file(struct file
>> *filp, struct poll_table_struct *po
>> poll_wait(filp, &info->wait_q, poll_tab);
>> - spin_lock(&info->lock);
>> + mutex_lock(&info->lock);
>> if (info->attr.mq_curmsgs)
>> retval = EPOLLIN | EPOLLRDNORM;
>> if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
>> retval |= EPOLLOUT | EPOLLWRNORM;
>> - spin_unlock(&info->lock);
>> + mutex_unlock(&info->lock);
>> return retval;
>> }
>> @@ -724,7 +724,7 @@ static int wq_sleep(struct mqueue_inode_info
>> *info, int sr,
>> /* memory barrier not required, we hold info->lock */
>> __set_current_state(TASK_INTERRUPTIBLE);
>> - spin_unlock(&info->lock);
>> + mutex_unlock(&info->lock);
>> time = schedule_hrtimeout_range_clock(timeout, 0,
>> HRTIMER_MODE_ABS, CLOCK_REALTIME);
>> @@ -734,7 +734,7 @@ static int wq_sleep(struct mqueue_inode_info
>> *info, int sr,
>> retval = 0;
>> goto out;
>> }
>> - spin_lock(&info->lock);
>> + mutex_lock(&info->lock);
>> /* we hold info->lock, so no memory barrier required */
>> if (READ_ONCE(ewp->state) == STATE_READY) {
>> @@ -752,7 +752,7 @@ static int wq_sleep(struct mqueue_inode_info
>> *info, int sr,
>> }
>> list_del(&ewp->list);
>> out_unlock:
>> - spin_unlock(&info->lock);
>> + mutex_unlock(&info->lock);
>> out:
>> return retval;
>> }
>> @@ -1125,7 +1125,7 @@ static int do_mq_timedsend(mqd_t mqdes, const
>> char __user *u_msg_ptr,
>> if (!info->node_cache)
>> new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
>> - spin_lock(&info->lock);
>> + mutex_lock(&info->lock);
>> if (!info->node_cache && new_leaf) {
>> /* Save our speculative allocation into the cache */
>> @@ -1166,7 +1166,7 @@ static int do_mq_timedsend(mqd_t mqdes, const
>> char __user *u_msg_ptr,
>> simple_inode_init_ts(inode);
>> }
>> out_unlock:
>> - spin_unlock(&info->lock);
>> + mutex_unlock(&info->lock);
>> wake_up_q(&wake_q);
>> out_free:
>> if (ret)
>> @@ -1230,7 +1230,7 @@ static int do_mq_timedreceive(mqd_t mqdes, char
>> __user *u_msg_ptr,
>> if (!info->node_cache)
>> new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
>> - spin_lock(&info->lock);
>> + mutex_lock(&info->lock);
>> if (!info->node_cache && new_leaf) {
>> /* Save our speculative allocation into the cache */
>> @@ -1242,7 +1242,7 @@ static int do_mq_timedreceive(mqd_t mqdes, char
>> __user *u_msg_ptr,
>> if (info->attr.mq_curmsgs == 0) {
>> if (f.file->f_flags & O_NONBLOCK) {
>> - spin_unlock(&info->lock);
>> + mutex_unlock(&info->lock);
>> ret = -EAGAIN;
>> } else {
>> wait.task = current;
>> @@ -1261,7 +1261,7 @@ static int do_mq_timedreceive(mqd_t mqdes, char
>> __user *u_msg_ptr,
>> /* There is now free space in queue. */
>> pipelined_receive(&wake_q, info);
>> - spin_unlock(&info->lock);
>> + mutex_unlock(&info->lock);
>> wake_up_q(&wake_q);
>> ret = 0;
>> }
>> @@ -1391,7 +1391,7 @@ static int do_mq_notify(mqd_t mqdes, const
>> struct sigevent *notification)
>> info = MQUEUE_I(inode);
>> ret = 0;
>> - spin_lock(&info->lock);
>> + mutex_lock(&info->lock);
>> if (notification == NULL) {
>> if (info->notify_owner == task_tgid(current)) {
>> remove_notification(info);
>> @@ -1424,7 +1424,7 @@ static int do_mq_notify(mqd_t mqdes, const
>> struct sigevent *notification)
>> info->notify_user_ns = get_user_ns(current_user_ns());
>> inode_set_atime_to_ts(inode, inode_set_ctime_current(inode));
>> }
>> - spin_unlock(&info->lock);
>> + mutex_unlock(&info->lock);
>> out_fput:
>> fdput(f);
>> out:
>> @@ -1470,7 +1470,7 @@ static int do_mq_getsetattr(int mqdes, struct
>> mq_attr *new, struct mq_attr *old)
>> inode = file_inode(f.file);
>> info = MQUEUE_I(inode);
>> - spin_lock(&info->lock);
>> + mutex_lock(&info->lock);
>> if (old) {
>> *old = info->attr;
>> @@ -1488,7 +1488,7 @@ static int do_mq_getsetattr(int mqdes, struct
>> mq_attr *new, struct mq_attr *old)
>> inode_set_atime_to_ts(inode, inode_set_ctime_current(inode));
>> }
>> - spin_unlock(&info->lock);
>> + mutex_unlock(&info->lock);
>> fdput(f);
>> return 0;
>> }
>
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