linux-kernel - [PATCH v3 2/4] lib/string_helpers.c: protect string_get_size() against blk

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Date:	Thu, 29 Oct 2015 17:30:48 +0100
From:	Vitaly Kuznetsov <vkuznets@...hat.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Rasmus Villemoes <linux@...musvillemoes.dk>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	James Bottomley <JBottomley@...n.com>,
	Kees Cook <keescook@...omium.org>, linux-kernel@...r.kernel.org
Subject: [PATCH v3 2/4] lib/string_helpers.c: protect string_get_size() against blk_size=0

Division by zero happens if blk_size=0 is supplied to string_get_size().
Add WARN_ON() and set size to 0 to report '0 B'.

Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
 lib/string_helpers.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lib/string_helpers.c b/lib/string_helpers.c
index f6c27dc..ff3575b 100644
--- a/lib/string_helpers.c
+++ b/lib/string_helpers.c
@@ -50,6 +50,11 @@ void string_get_size(u64 size, u32 blk_size, const enum string_size_units units,
 
 	tmp[0] = '\0';
 	i = 0;
+
+	/* Calling string_get_size() with blk_size=0 is wrong! */
+	if (WARN_ON(!blk_size))
+		size = 0;
+
 	if (!size)
 		goto out;
 
-- 
2.4.3

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