linux-kernel - [PATCH 4/7] Prevent u32_format_array from returning a size too big

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Message-ID: <1516dd65-5128-22ad-524a-a6474010e7ae@x41-dsec.de>
Date:   Wed, 11 Oct 2017 10:28:32 +0200
From:   Eric Sesterhenn <eric.sesterhenn@...-dsec.de>
To:     linux-kernel@...r.kernel.org
Subject: [PATCH 4/7] Prevent u32_format_array from returning a size too big


snprintf can return a value bigger than the size of the buffer,
in this case we return a size that is longer than the string.

Signed-off-by: Eric Sesterhenn <eric.sesterhenn@...-dsec.de>
---
 fs/debugfs/file.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index 6dabc4a10396..2a5cd7a088fc 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -904,6 +904,9 @@ static size_t u32_format_array(char *buf, size_t
bufsize,
 		char term = array_size ? ' ' : '\n';

 		len = snprintf(buf, bufsize, "%u%c", *array++, term);
+		if (len >= bufsize)
+			return ret+bufsize;
+
 		ret += len;

 		buf += len;

-- 
Eric Sesterhenn (Principal Security Consultant)
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