[PATCH] epoll: handle timeout overflow

Handle the timeout upper boundary for epoll.

Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 403b90a..4284cd3 100644 (file)
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -101,6 +101,10 @@
 /* Maximum number of poll wake up nests we are allowing */
 #define EP_MAX_POLLWAKE_NESTS 4
 
+/* Maximum msec timeout value storeable in a long int */
+#define EP_MAX_MSTIMEO min(1000ULL * MAX_SCHEDULE_TIMEOUT / HZ, (LONG_MAX - 999ULL) / HZ)
+
+
 struct epoll_filefd {
        struct file *file;
        int fd;
@@ -1506,8 +1510,8 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
         * and the overflow condition. The passed timeout is in milliseconds,
         * that why (t * HZ) / 1000.
         */
-       jtimeout = timeout == -1 || timeout > (MAX_SCHEDULE_TIMEOUT - 1000) / HZ ?
-               MAX_SCHEDULE_TIMEOUT: (timeout * HZ + 999) / 1000;
+       jtimeout = (timeout < 0 || timeout >= EP_MAX_MSTIMEO) ?
+               MAX_SCHEDULE_TIMEOUT : (timeout * HZ + 999) / 1000;
 
 retry:
        write_lock_irqsave(&ep->lock, flags);