[PATCH v3 1/2] PCI: Avoid panic when PCI IO resource's size is not page aligned

[Yisheng Xie]

Zhou reported a bug on Hisilicon arm64 D06 platform with 64KB page size:

 [    2.470908] kernel BUG at lib/ioremap.c:72!
 [    2.475079] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
 [    2.480551] Modules linked in:
 [    2.483594] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.16.0-rc7-00062-g0b41260-dirty #23
 [    2.491756] Hardware name: Huawei D06/D06, BIOS Hisilicon D06 UEFI Nemo 2.0 RC0 - B120 03/23/2018
 [    2.500614] pstate: 80c00009 (Nzcv daif +PAN +UAO)
 [    2.505395] pc : ioremap_page_range+0x268/0x36c
 [    2.509912] lr : pci_remap_iospace+0xe4/0x100
 [...]
 [    2.603733] Call trace:
 [    2.606168]  ioremap_page_range+0x268/0x36c
 [    2.610337]  pci_remap_iospace+0xe4/0x100
 [    2.614334]  acpi_pci_probe_root_resources+0x1d4/0x214
 [    2.619460]  pci_acpi_root_prepare_resources+0x18/0xa8
 [    2.624585]  acpi_pci_root_create+0x98/0x214
 [    2.628843]  pci_acpi_scan_root+0x124/0x20c
 [    2.633013]  acpi_pci_root_add+0x224/0x494
 [    2.637096]  acpi_bus_attach+0xf8/0x200
 [    2.640918]  acpi_bus_attach+0x98/0x200
 [    2.644740]  acpi_bus_attach+0x98/0x200
 [    2.648562]  acpi_bus_scan+0x48/0x9c
 [    2.652125]  acpi_scan_init+0x104/0x268
 [    2.655948]  acpi_init+0x308/0x374
 [    2.659337]  do_one_initcall+0x48/0x14c
 [    2.663160]  kernel_init_freeable+0x19c/0x250
 [    2.667504]  kernel_init+0x10/0x100
 [    2.670979]  ret_from_fork+0x10/0x18

The cause is the size of PCI IO resource is 32KB, which is 4K aligned but
not 64KB aligned, however, ioremap_page_range() request the range as page
aligned or it will trigger a BUG_ON() on ioremap_pte_range() it calls, as
ioremap_pte_range increase the addr by PAGE_SIZE, which makes addr != end
until trigger BUG_ON, if its incoming end is not page aligned. More detail
trace is as following:

 ioremap_page_range
 -> ioremap_p4d_range
    -> ioremap_p4d_range
       -> ioremap_pud_range
          -> ioremap_pmd_range
             -> ioremap_pte_range

This patch avoid panic by return -EINVAL if vaddr or resource size is not
page aligned.

Reported-by: Zhou Wang <wangzhou1@xxxxxxxxxxxxx>
Tested-by: Xiaojun Tan <tanxiaojun@xxxxxxxxxx>
Signed-off-by: Yisheng Xie <xieyisheng1@xxxxxxxxxx>
---
v3:
 - pci_remap_iospace() sanitize its arguments instead - per Rafael

v2:
 - Let the caller of ioremap_page_range() align the request by PAGE_SIZE - per Toshi

 drivers/pci/pci.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index dbfe7c4..0eb0381 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3544,6 +3544,9 @@ int pci_remap_iospace(const struct resource *res, phys_addr_t phys_addr)
 	if (res->end > IO_SPACE_LIMIT)
 		return -EINVAL;
 
+	if (!PAGE_ALIGNED(vaddr) || !PAGE_ALIGNED(resource_size(res)))
+		return -EINVAL;
+
 	return ioremap_page_range(vaddr, vaddr + resource_size(res), phys_addr,
 				  pgprot_device(PAGE_KERNEL));
 #else
-- 
1.7.12.4