In the Linux kernel, the following vulnerability has been resolved: ata: ahci: fail probe if BAR...

In the Linux kernel, the following vulnerability has been resolved:

ata: ahci: fail probe if BAR too small for claimed ports

When an AHCI controller is disabled in BIOS, its HOST_CAP register may contain a bogus value, e.g. 0xFFFFFFFF.

Since CAP.NP (Number of Ports) is a zeroes based 5-bit register field, a value of 0x1f means 32 ports. If CAP.NP claims more ports than can physically fit within the mapped BAR region, accessing port registers beyond the BAR boundary causes a kernel panic.

Add validation in ahci_init_one() to check that the BAR size is sufficient for the number of ports claimed in CAP.NP. The check calculates the required MMIO size as:

required_size = 0x100 (global registers) + max_ports * 0x80

If required_size exceeds the actual BAR size, the probe fails with -ENODEV, preventing the panic and providing a clear error message.

[cassel: commit log]