linux-kernel - [PATCH RFC 3/5] kdbus: do explicit overflow check in kdbus_conn_quota

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Date:	Sun, 28 Jun 2015 16:17:32 +0300
From:	Sergei Zviagintsev <sergei@...v.net>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Daniel Mack <daniel@...que.org>,
	David Herrmann <dh.herrmann@...glemail.com>,
	Djalal Harouni <tixxdz@...ndz.org>
Cc:	linux-kernel@...r.kernel.org, Sergei Zviagintsev <sergei@...v.net>
Subject: [PATCH RFC 3/5] kdbus: do explicit overflow check in kdbus_conn_quota_inc()

Replace the use of max() with explicit and obvious overflow check.

Signed-off-by: Sergei Zviagintsev <sergei@...v.net>
---
 ipc/kdbus/connection.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/ipc/kdbus/connection.c b/ipc/kdbus/connection.c
index af044f93c14f..1d44e280eff0 100644
--- a/ipc/kdbus/connection.c
+++ b/ipc/kdbus/connection.c
@@ -668,9 +668,11 @@ int kdbus_conn_quota_inc(struct kdbus_conn *c, struct kdbus_user *u,
 
 	id = u ? u->id : KDBUS_USER_KERNEL_ID;
 	if (id >= c->n_quota) {
-		unsigned int users;
+		unsigned int users = KDBUS_ALIGN8(id) + 8;
+
+		if (users < id) /* overflow */
+			users = id;
 
-		users = max(KDBUS_ALIGN8(id) + 8, id);
 		quota = krealloc(c->quota, users * sizeof(*quota),
 				 GFP_KERNEL | __GFP_ZERO);
 		if (!quota)
-- 
1.8.3.1

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