HID: amd_sfh: Validate PCI BAR size before mapping

Overview

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

HID: amd_sfh: Validate PCI BAR size before mapping

The amd_sfh driver maps PCI BAR 2 using pcim_iomap_regions() and subsequently accesses MMIO registers at offsets up to 0x10958 (e.g., AMD_P2C_MSG3 at 0x1068C). However, the driver never validates that the BAR size is large enough to cover these accesses. If the driver is bound to a device with a smaller BAR 2, this leads to an out-of-bounds memory access and a page fault during the probe function.

For example, a page fault can occur when reading from privdata->mmio + AMD_P2C_MSG3 in mp2_select_ops():

BUG: unable to handle page fault for address: ffffc9000390368c PGD 100000067 P4D 100000067 PUD 1012c1067 PMD 105b64067 PTE 0 Oops: Oops: 0000 [#1] SMP KASAN NOPTI RIP: 0010:readl arch/x86/include/asm/io.h:59 [inline] RIP: 0010:mp2_select_ops drivers/hid/amd-sfh-hid/amd_sfh_pcie.c:282 [inline] RIP: 0010:amd_mp2_pci_probe+0x337/0x5f0 drivers/hid/amd-sfh-hid/amd_sfh_pcie.c:487 Call Trace: <TASK> local_pci_probe drivers/pci/pci-driver.c:332 [inline] pci_call_probe drivers/pci/pci-driver.c:394 [inline] __pci_device_probe drivers/pci/pci-driver.c:455 [inline] pci_device_probe+0x431/0xc90 drivers/pci/pci-driver.c:489

Fix this by verifying that the length of BAR 2 is at least 128KB before attempting to map it. Since the maximum accessed offset is 0x10958, and PCI BAR sizes are powers of 2, any legitimate hardware will have a BAR size of at least 128KB.

Affected

• Linux >= 4f567b9f8141a86c7d878fadf136e5d1408e3e61 < 92bf2883da0306ab9d1eb794acd1058fc5088ebc
• Linux >= 4f567b9f8141a86c7d878fadf136e5d1408e3e61 < 7b3747d77767f066ccf4a9e8e3a8381643ab5368
• Linux >= 4f567b9f8141a86c7d878fadf136e5d1408e3e61 < 5ff24aa7af0bca0780fe4e6effce902065f2c0a7
• Linux >= 4f567b9f8141a86c7d878fadf136e5d1408e3e61 < dc687489131559ee52f447592f6d039a5a013061
• Linux >= 4f567b9f8141a86c7d878fadf136e5d1408e3e61 < 5f9e2ecb725adced013fbf5f94b9f185fad2e7d9
• Linux >= 4f567b9f8141a86c7d878fadf136e5d1408e3e61 < ee25833f037fa22d23ffdbfeebabe3579e8a0346
• Linux >= 4f567b9f8141a86c7d878fadf136e5d1408e3e61 < 65bcc5f89704efe5b9d69d4ea2c1002d90c31382
• Linux 5.11

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.