dpaa2-switch: prevent ZERO_SIZE_PTR dereference when num_ifs is zero

[ Upstream commit ed48a84a72fefb20a82dd90a7caa7807e90c6f66 ]

The driver allocates arrays for ports, FDBs, and filter blocks using
kcalloc() with ethsw->sw_attr.num_ifs as the element count. When the
device reports zero interfaces (either due to hardware configuration
or firmware issues), kcalloc(0, ...) returns ZERO_SIZE_PTR (0x10)
instead of NULL.

Later in dpaa2_switch_probe(), the NAPI initialization unconditionally
accesses ethsw->ports[0]->netdev, which attempts to dereference
ZERO_SIZE_PTR (address 0x10), resulting in a kernel panic.

Add a check to ensure num_ifs is greater than zero after retrieving
device attributes. This prevents the zero-sized allocations and
subsequent invalid pointer dereference.

Reported-by: Yuhao Jiang <danisjiang@gmail.com>
Reported-by: Junrui Luo <moonafterrain@outlook.com>
Fixes: 0b1b71370458 ("staging: dpaa2-switch: handle Rx path on control interface")
Signed-off-by: Junrui Luo <moonafterrain@outlook.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/SYBPR01MB7881BEABA8DA896947962470AF91A@SYBPR01MB7881.ausprd01.prod.outlook.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

0 files changed, 0 insertions, 0 deletions