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>
---
Changes in v2:
    - Add 'fixes' tag
---
 drivers/net/arcnet/com20020-pci.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/arcnet/com20020-pci.c b/drivers/net/arcnet/com20020-pci.c
index 6382e1937cca..c580acb8b1d3 100644
--- a/drivers/net/arcnet/com20020-pci.c
+++ b/drivers/net/arcnet/com20020-pci.c
@@ -138,6 +138,9 @@ static int com20020pci_probe(struct pci_dev *pdev,
 		return -ENOMEM;
 
 	ci = (struct com20020_pci_card_info *)id->driver_data;
+	if (!ci)
+		return -EINVAL;
+
 	priv->ci = ci;
 	mm = &ci->misc_map;
 
-- 
2.25.1

Hello:

This patch was applied to netdev/net.git (master)
by David S. Miller <davem@davemloft.net>:

On Wed,  2 Mar 2022 20:24:23 +0800 you wrote:
> 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:
> 
> [...]

Here is the summary with links:
  - [v2] net: arcnet: com20020: Fix null-ptr-deref in com20020pci_probe()
    https://git.kernel.org/netdev/net/c/bd6f1fd5d33d

You are awesome, thank you!
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