[Patch] Limit max_user_watches to prevent integer overflow.

[Robin Holt]

Subject: [Patch] Limit max_user_watches to prevent integer overflow.

On a 16TB machine, max_user_watches has an integer overflow.  Limit it
to INT_MAX.

Signed-off-by: Robin Holt <holt@xxxxxxx>
To: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
To: Davide Libenzi <davidel@xxxxxxxxxxxxxxx>
To: linux-kernel@xxxxxxxxxxxxxxx
To: Pekka Enberg <penberg@xxxxxxxxxxxxxx>

---

 fs/eventpoll.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Index: pv1010933/fs/eventpoll.c
===================================================================
--- pv1010933.orig/fs/eventpoll.c	2010-10-02 06:35:37.000000000 -0500
+++ pv1010933/fs/eventpoll.c	2010-10-02 06:38:06.479823590 -0500
@@ -1415,13 +1415,14 @@ SYSCALL_DEFINE6(epoll_pwait, int, epfd,
 static int __init eventpoll_init(void)
 {
 	struct sysinfo si;
+	long limit;
 
 	si_meminfo(&si);
 	/*
 	 * Allows top 4% of lomem to be allocated for epoll watches (per user).
 	 */
-	max_user_watches = (((si.totalram - si.totalhigh) / 25) << PAGE_SHIFT) /
-		EP_ITEM_COST;
+	limit = (((si.totalram - si.totalhigh) / 25) << PAGE_SHIFT) / EP_ITEM_COST;
+	max_user_watches = min_t(long, limit, INT_MAX);
 
 	/* Initialize the structure used to perform safe poll wait head wake ups */
 	ep_nested_calls_init(&poll_safewake_ncalls);

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