I analyze the potential sleeping issue of the following processes:
Thread A Thread B
... netlink_create //create sock
do_mq_notify ...
sock = netlink_getsockbyfilp ... //hold sock
info->notify_sock = sock; ...
... netlink_sendmsg
... skb = netlink_alloc_large_skb //skb->head is vmalloced
... netlink_unicast
... sk = netlink_getsockbyportid
... netlink_sendskb
... __netlink_sendskb
... skb_queue_tail //put skb to sk_receive_queue
mqueue_flush_file
spin_lock
remove_notification
netlink_sendskb
sock_put //put sock
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 <[email protected]>
---
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;
}
--
2.34.1