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From:   Demi Marie Obenour <demi@invisiblethingslab.com>
To:     Jens Axboe <axboe@kernel.dk>,
        =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= <roger.pau@citrix.com>,
        Alasdair Kergon <agk@redhat.com>,
        Mike Snitzer <snitzer@kernel.org>, dm-devel@redhat.com
Cc:     Demi Marie Obenour <demi@invisiblethingslab.com>,
        =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?= 
        <marmarek@invisiblethingslab.com>, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org,
        stable@vger.kernel.org
Subject: [PATCH v2 03/16] device-mapper: do not allow targets to overlap 'struct dm_ioctl'
Date:   Tue, 30 May 2023 16:31:03 -0400
Message-Id: <20230530203116.2008-4-demi@invisiblethingslab.com>
In-Reply-To: <20230530203116.2008-1-demi@invisiblethingslab.com>
References: <20230530203116.2008-1-demi@invisiblethingslab.com>
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This prevents dm_split_args() from corrupting this struct.

Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
---
 drivers/md/dm-ioctl.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 64e8f16d344c47057de5e2d29e3d63202197dca0..a1d5fe64e1d0d9d3dcb06924249b89fe661944ab 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1444,6 +1444,12 @@ static int populate_table(struct dm_table *table,
 		return -EINVAL;
 	}
 
+	if (next < sizeof(struct dm_ioctl)) {
+		DMERR("%s: first target spec (offset %u) overlaps 'struct dm_ioctl'",
+		      __func__, next);
+		return -EINVAL;
+	}
+
 	for (i = 0; i < param->target_count; i++) {
 
 		r = next_target(spec, next, end, &spec, &target_params);
-- 
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab