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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, Zheyu Ma <zheyuma97@gmail.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.14 31/42] net: arcnet: com20020: Fix null-ptr-deref in com20020pci_probe()
Date:   Mon,  7 Mar 2022 10:19:05 +0100
Message-Id: <20220307091637.058914754@linuxfoundation.org>
In-Reply-To: <20220307091636.146155347@linuxfoundation.org>
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From: Zheyu Ma <zheyuma97@gmail.com>

commit bd6f1fd5d33dfe5d1b4f2502d3694a7cc13f166d upstream.

During driver initialization, the pointer of card info, i.e. the
variable 'ci' is required. However, the definition of
'com20020pci_id_table' reveals that this field is empty for some
devices, which will cause null pointer dereference when initializing
these devices.

The following log reveals it:

[    3.973806] KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
[    3.973819] RIP: 0010:com20020pci_probe+0x18d/0x13e0 [com20020_pci]
[    3.975181] Call Trace:
[    3.976208]  local_pci_probe+0x13f/0x210
[    3.977248]  pci_device_probe+0x34c/0x6d0
[    3.977255]  ? pci_uevent+0x470/0x470
[    3.978265]  really_probe+0x24c/0x8d0
[    3.978273]  __driver_probe_device+0x1b3/0x280
[    3.979288]  driver_probe_device+0x50/0x370

Fix this by checking whether the 'ci' is a null pointer first.

Fixes: 8c14f9c70327 ("ARCNET: add com20020 PCI IDs with metadata")
Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/arcnet/com20020-pci.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/net/arcnet/com20020-pci.c
+++ b/drivers/net/arcnet/com20020-pci.c
@@ -136,6 +136,9 @@ static int com20020pci_probe(struct pci_
 		return -ENOMEM;
 
 	ci = (struct com20020_pci_card_info *)id->driver_data;
+	if (!ci)
+		return -EINVAL;
+
 	priv->ci = ci;
 	mm = &ci->misc_map;