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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Thiago Macieira <thiago.macieira@intel.com>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Sasha Levin <sashal@kernel.org>, stable@kernel.org
Subject: [PATCH 4.9 08/64] fix multiplication overflow in copy_fdtable()
Date:   Tue, 26 May 2020 20:52:37 +0200
Message-Id: <20200526183916.239049463@linuxfoundation.org>
In-Reply-To: <20200526183913.064413230@linuxfoundation.org>
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From: Al Viro <viro@zeniv.linux.org.uk>

[ Upstream commit 4e89b7210403fa4a8acafe7c602b6212b7af6c3b ]

cpy and set really should be size_t; we won't get an overflow on that,
since sysctl_nr_open can't be set above ~(size_t)0 / sizeof(void *),
so nr that would've managed to overflow size_t on that multiplication
won't get anywhere near copy_fdtable() - we'll fail with EMFILE
before that.

Cc: stable@kernel.org # v2.6.25+
Fixes: 9cfe015aa424 (get rid of NR_OPEN and introduce a sysctl_nr_open)
Reported-by: Thiago Macieira <thiago.macieira@intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/file.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/file.c b/fs/file.c
index 09aac4d4729b..82d3f925bab3 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -89,7 +89,7 @@ static void copy_fd_bitmaps(struct fdtable *nfdt, struct fdtable *ofdt,
  */
 static void copy_fdtable(struct fdtable *nfdt, struct fdtable *ofdt)
 {
-	unsigned int cpy, set;
+	size_t cpy, set;
 
 	BUG_ON(nfdt->max_fds < ofdt->max_fds);
 
-- 
2.25.1