linux-kernel - [PATCH 5.8 209/232] fs/ufs: avoid potential u32 multiplication overflow

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Message-Id: <20200820091622.934009523@linuxfoundation.org>
Date:   Thu, 20 Aug 2020 11:21:00 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Colin Ian King <colin.king@...onical.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Evgeniy Dushistov <dushistov@...l.ru>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.8 209/232] fs/ufs: avoid potential u32 multiplication overflow

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

[ Upstream commit 88b2e9b06381551b707d980627ad0591191f7a2d ]

The 64 bit ino is being compared to the product of two u32 values,
however, the multiplication is being performed using a 32 bit multiply so
there is a potential of an overflow.  To be fully safe, cast uspi->s_ncg
to a u64 to ensure a 64 bit multiplication occurs to avoid any chance of
overflow.

Fixes: f3e2a520f5fb ("ufs: NFS support")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Cc: Evgeniy Dushistov <dushistov@...l.ru>
Cc: Alexey Dobriyan <adobriyan@...il.com>
Link: http://lkml.kernel.org/r/20200715170355.1081713-1-colin.king@canonical.com
Addresses-Coverity: ("Unintentional integer overflow")
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/ufs/super.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ufs/super.c b/fs/ufs/super.c
index 1da0be667409b..e3b69fb280e8c 100644
--- a/fs/ufs/super.c
+++ b/fs/ufs/super.c
@@ -101,7 +101,7 @@ static struct inode *ufs_nfs_get_inode(struct super_block *sb, u64 ino, u32 gene
 	struct ufs_sb_private_info *uspi = UFS_SB(sb)->s_uspi;
 	struct inode *inode;
 
-	if (ino < UFS_ROOTINO || ino > uspi->s_ncg * uspi->s_ipg)
+	if (ino < UFS_ROOTINO || ino > (u64)uspi->s_ncg * uspi->s_ipg)
 		return ERR_PTR(-ESTALE);
 
 	inode = ufs_iget(sb, ino);
-- 
2.25.1