linux-kernel - [PATCH] fs: sync_file_range: avoid overflowing signed calculation

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Message-Id: <1417493050-13594-6-git-send-email-sasha.levin@oracle.com>
Date:	Mon,  1 Dec 2014 23:04:10 -0500
From:	Sasha Levin <sasha.levin@...cle.com>
To:	linux-kernel@...r.kernel.org
Cc:	Sasha Levin <sasha.levin@...cle.com>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	linux-fsdevel@...r.kernel.org
Subject: [PATCH] fs: sync_file_range: avoid overflowing signed calculation

When calculating the end byte for the sync we preform an addition which might
result in an overflow, which is undefined. Avoid it by doing unsigned
addition.

Signed-off-by: Sasha Levin <sasha.levin@...cle.com>
---
 fs/sync.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/sync.c b/fs/sync.c
index 6ccfc38..f9cb38f 100644
--- a/fs/sync.c
+++ b/fs/sync.c
@@ -286,7 +286,7 @@ SYSCALL_DEFINE4(sync_file_range, int, fd, loff_t, offset, loff_t, nbytes,
 	if (flags & ~VALID_FLAGS)
 		goto out;
 
-	endbyte = offset + nbytes;
+	endbyte = offset + (u64)nbytes;
 
 	if ((s64)offset < 0)
 		goto out;
-- 
1.7.10.4

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