linux-kernel - [PATCH][next] fs/ntfs3: Fix integer overflow in multiplication

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Message-Id: <20210816163025.81770-1-colin.king@canonical.com>
Date:   Mon, 16 Aug 2021 17:30:25 +0100
From:   Colin King <colin.king@...onical.com>
To:     Konstantin Komarov <almaz.alexandrovich@...agon-software.com>,
        ntfs3@...ts.linux.dev
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH][next] fs/ntfs3: Fix integer overflow in multiplication

From: Colin Ian King <colin.king@...onical.com>

The multiplication of the u32 data_size with a int is being performed
using 32 bit arithmetic however the results is being assigned to the
variable nbits that is a size_t (64 bit) value. Fix a potential
integer overflow by casting the u32 value to a size_t before the
multiply to use a size_t sized bit multiply operation.

Addresses-Coverity: ("Unintentional integer overflow")
Fixes: 82cae269cfa9 ("fs/ntfs3: Add initialization of super block")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 fs/ntfs3/index.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ntfs3/index.c b/fs/ntfs3/index.c
index 6aa9540ece47..9386c551e208 100644
--- a/fs/ntfs3/index.c
+++ b/fs/ntfs3/index.c
@@ -2012,7 +2012,7 @@ static int indx_shrink(struct ntfs_index *indx, struct ntfs_inode *ni,
 		unsigned long pos;
 		const unsigned long *bm = resident_data(b);
 
-		nbits = le32_to_cpu(b->res.data_size) * 8;
+		nbits = (size_t)le32_to_cpu(b->res.data_size) * 8;
 
 		if (bit >= nbits)
 			return 0;
-- 
2.32.0