Re: [syzbot] Re: [syzbot] [fs?] BUG: corrupted list in remove_wait_queue (2)

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Subject: Re: [syzbot] [fs?] BUG: corrupted list in remove_wait_queue (2)
Author: lizhi.xu@xxxxxxxxxxxxx

#syz test

diff --git a/fs/select.c b/fs/select.c
index 7da531b1cf6b..63dd2fb58447 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -977,6 +977,7 @@ static int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds,
  	struct poll_list *walk = head;
 	unsigned int todo = nfds;
 	unsigned int len;
+	static DEFINE_MUTEX(syspoll_lock);
 
 	if (nfds > rlimit(RLIMIT_NOFILE))
 		return -EINVAL;
@@ -1005,9 +1006,11 @@ static int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds,
 		}
 	}
 
+	mutex_lock(&syspoll_lock);
 	poll_initwait(&table);
 	fdcount = do_poll(head, &table, end_time);
 	poll_freewait(&table);
+	mutex_unlock(&syspoll_lock);
 
 	if (!user_write_access_begin(ufds, nfds * sizeof(*ufds)))
 		goto out_fds;