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

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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.

Reported-by: liyouhong <liyouhong@kylinos.cn>
Closes: https://lore.kernel.org/all/20260422080322.1006592-1-dayou5941@163.com/
Suggested-by: Damien Le Moal <dlemoal@kernel.org>
Suggested-by: Niklas Cassel <cassel@kernel.org>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: liyouhong <liyouhong@kylinos.cn>
[cassel: commit log]
Signed-off-by: Niklas Cassel <cassel@kernel.org>
This commit is contained in:
liyouhong
2026-04-28 10:09:35 +08:00
committed by Niklas Cassel
parent 3f8e2146d0
commit c4086c6e1a
1 changed files with 22 additions and 0 deletions
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22
drivers/ata/ahci.c
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@@ -1888,6 +1888,24 @@ static ssize_t remapped_nvme_show(struct device *dev,
static DEVICE_ATTR_RO(remapped_nvme);
static int ahci_validate_bar_size(struct pci_dev *pdev, int bar,
struct ahci_host_priv *hpriv)
{
u32 cap = readl(hpriv->mmio + HOST_CAP);
unsigned int max_ports = ahci_nr_ports(cap);
u32 last_port_end = 0x100 + (max_ports * 0x80);
resource_size_t bar_size = pci_resource_len(pdev, bar);
if (last_port_end > bar_size) {
dev_warn(&pdev->dev,
"BAR%d too small for %u ports (last port ends at %#x, BAR %pa)\n",
bar, max_ports, last_port_end, &bar_size);
return -ENODEV;
}
return 0;
}
static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
{
unsigned int board_id = ent->driver_data;
@@ -1988,6 +2006,10 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
if (!hpriv->mmio)
return -ENOMEM;
rc = ahci_validate_bar_size(pdev, ahci_pci_bar, hpriv);
if (rc)
return rc;
/* detect remapped nvme devices */
ahci_remap_check(pdev, ahci_pci_bar, hpriv);