[PATCH 6.18 129/314] net: arcnet: com20020-pci: fix support for 2.5Mbit cards

Sasha Levin
2026-03-10T11:26:43Z

From: Ethan Nelson-Moore <enelsonmoore@gmail.com>

[ Upstream commit c7d9be66b71af490446127c6ffcb66d6bb71b8b9 ]

Commit 8c14f9c70327 ("ARCNET: add com20020 PCI IDs with metadata")
converted the com20020-pci driver to use a card info structure instead
of a single flag mask in driver_data. However, it failed to take into
account that in the original code, driver_data of 0 indicates a card
with no special flags, not a card that should not have any card info
structure. This introduced a null pointer dereference when cards with
no flags were probed.

Commit bd6f1fd5d33d ("net: arcnet: com20020: Fix null-ptr-deref in
com20020pci_probe()") then papered over this issue by rejecting cards
with no driver_data instead of resolving the problem at its source.

Fix the original issue by introducing a new card info structure for
2.5Mbit cards that does not set any flags and using it if no
driver_data is present.

Fixes: 8c14f9c70327 ("ARCNET: add com20020 PCI IDs with metadata")
Fixes: bd6f1fd5d33d ("net: arcnet: com20020: Fix null-ptr-deref in com20020pci_probe()")
Cc: stable@vger.kernel.org
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Ethan Nelson-Moore <enelsonmoore@gmail.com>
Link: https://patch.msgid.link/20260213045510.32368-1-enelsonmoore@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/arcnet/com20020-pci.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/net/arcnet/com20020-pci.c b/drivers/net/arcnet/com20020-pci.c
index 0472bcdff1307..b5729d6c0b47c 100644
--- a/drivers/net/arcnet/com20020-pci.c
+++ b/drivers/net/arcnet/com20020-pci.c
@@ -115,6 +115,8 @@ static const struct attribute_group com20020_state_group = {
.attrs = com20020_state_attrs,
};

+static struct com20020_pci_card_info card_info_2p5mbit;
+
static void com20020pci_remove(struct pci_dev *pdev);

static int com20020pci_probe(struct pci_dev *pdev,
@@ -140,7 +142,7 @@ static int com20020pci_probe(struct pci_dev *pdev,

ci = (struct com20020_pci_card_info *)id->driver_data;
if (!ci)
- return -EINVAL;
+ ci = &card_info_2p5mbit;

priv->ci = ci;
mm = &ci->misc_map;
@@ -347,6 +349,18 @@ static struct com20020_pci_card_info card_info_5mbit = {
.flags = ARC_IS_5MBIT,
};

+static struct com20020_pci_card_info card_info_2p5mbit = {
+ .name = "ARC-PCI",
+ .devcount = 1,
+ .chan_map_tbl = {
+ {
+ .bar = 2,
+ .offset = 0x00,
+ .size = 0x08,
+ },
+ },
+};
+
static struct com20020_pci_card_info card_info_sohard = {
.name = "SOHARD SH ARC-PCI",
.devcount = 1,
--
2.51.0