linux-kernel - [PATCH 1/1] kernel/fork.c: avoid division by zero

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 16 Feb 2015 19:00:44 +0100
From:	Heinrich Schuchardt <xypron.glpk@....de>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Oleg Nesterov <oleg@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	Vladimir Davydov <vdavydov@...allels.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	David Rientjes <rientjes@...gle.com>,
	Kees Cook <keescook@...omium.org>,
	Aaron Tomlin <atomlin@...hat.com>,
	linux-kernel@...r.kernel.org,
	Heinrich Schuchardt <xypron.glpk@....de>
Subject: [PATCH 1/1] kernel/fork.c: avoid division by zero

PAGE_SIZE is not guaranteed to be equal to or less than 8 times the
THREAD_SIZE.

E.g. architecture hexagon may have page size 1M and thread size 4096.

This would lead to a division by zero.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@....de>
---
 kernel/fork.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index cf65139..71e2583 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -273,7 +273,8 @@ void __init fork_init(unsigned long mempages)
 	 * value: the thread structures can take up at most half
 	 * of memory.
 	 */
-	max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
+	max_threads = (u64) PAGE_SIZE * (u64) mempages
+		    / (u64) THREAD_SIZE / 8UL;
 
 	/*
 	 * we need to allow at least 20 threads to boot a system
-- 
2.1.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/