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* [PATCH RFC v2] HID: amd_sfh: Validate PCI BAR size before mapping
@ 2026-08-26  8:17 syzbot
  2026-08-26  9:19 ` Slawomir Stepien
  0 siblings, 1 reply; 2+ messages in thread
From: syzbot @ 2026-08-26  8:17 UTC (permalink / raw)
  To: syzkaller-upstream-moderation; +Cc: sst, syzbot

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.

Fixes: 4f567b9f8141 ("SFH: PCIe driver to add support of AMD sensor fusion hub")
Assisted-by: Gemini:gemini-3.7-flash Gemini:gemini-3.1-pro-preview syzbot
Reported-by: syzbot+4eadd4dfe9e66522bae8@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=4eadd4dfe9e66522bae8
Link: https://syzkaller.appspot.com/ai_job?id=ae80612d-4fc5-4b7a-83bb-894e0a14dc5e
To: "Basavaraj Natikar" <basavaraj.natikar@amd.com>
To: "Benjamin Tissoires" <bentiss@kernel.org>
To: "Jiri Kosina" <jikos@kernel.org>
To: <linux-input@vger.kernel.org>
To: "Sandeep Singh" <sandeep.singh@amd.com>
Cc: <linux-kernel@vger.kernel.org>
Cc: "Mario Limonciello (AMD)" <superm1@kernel.org>

---
v2:
- Define AMD_SFH_MIN_BAR_SIZE macro instead of hardcoded 128 * 1024
- Use AMD_SFH_MIN_BAR_SIZE in amd_sfh1_1_init()

v1:
https://lore.kernel.org/all/f83daf97-4762-4a67-bac7-615b34d1b661@mail.kernel.org/T/
---
diff --git a/drivers/hid/amd-sfh-hid/amd_sfh_common.h b/drivers/hid/amd-sfh-hid/amd_sfh_common.h
index 78f830c13..c0c324565 100644
--- a/drivers/hid/amd-sfh-hid/amd_sfh_common.h
+++ b/drivers/hid/amd-sfh-hid/amd_sfh_common.h
@@ -17,6 +17,8 @@
 #define PCI_DEVICE_ID_AMD_MP2		0x15E4
 #define PCI_DEVICE_ID_AMD_MP2_1_1	0x164A
 
+#define AMD_SFH_MIN_BAR_SIZE		(128 * 1024)
+
 #define AMD_C2P_MSG(regno) (0x10500 + ((regno) * 4))
 #define AMD_P2C_MSG(regno) (0x10680 + ((regno) * 4))
 
diff --git a/drivers/hid/amd-sfh-hid/amd_sfh_pcie.c b/drivers/hid/amd-sfh-hid/amd_sfh_pcie.c
index 4b81cebdc..d870585a0 100644
--- a/drivers/hid/amd-sfh-hid/amd_sfh_pcie.c
+++ b/drivers/hid/amd-sfh-hid/amd_sfh_pcie.c
@@ -451,6 +451,11 @@ static int amd_mp2_pci_probe(struct pci_dev *pdev, const struct pci_device_id *i
 	if (rc)
 		return rc;
 
+	if (pci_resource_len(pdev, 2) < AMD_SFH_MIN_BAR_SIZE) {
+		dev_err(&pdev->dev, "BAR 2 is too small\n");
+		return -EINVAL;
+	}
+
 	rc = pcim_iomap_regions(pdev, BIT(2), DRIVER_NAME);
 	if (rc)
 		return rc;
diff --git a/drivers/hid/amd-sfh-hid/sfh1_1/amd_sfh_init.c b/drivers/hid/amd-sfh-hid/sfh1_1/amd_sfh_init.c
index b0bab2a1d..0afc596b5 100644
--- a/drivers/hid/amd-sfh-hid/sfh1_1/amd_sfh_init.c
+++ b/drivers/hid/amd-sfh-hid/sfh1_1/amd_sfh_init.c
@@ -388,12 +388,12 @@ int amd_sfh1_1_init(struct amd_mp2_dev *mp2)
 	int rc;
 
 	phy_base <<= 21;
-	if (!devm_request_mem_region(dev, phy_base, 128 * 1024, "amd_sfh")) {
+	if (!devm_request_mem_region(dev, phy_base, AMD_SFH_MIN_BAR_SIZE, "amd_sfh")) {
 		dev_dbg(dev, "can't reserve mmio registers\n");
 		return -ENOMEM;
 	}
 
-	mp2->vsbase = devm_ioremap(dev, phy_base, 128 * 1024);
+	mp2->vsbase = devm_ioremap(dev, phy_base, AMD_SFH_MIN_BAR_SIZE);
 	if (!mp2->vsbase) {
 		dev_dbg(dev, "failed to remap vsbase\n");
 		return -ENOMEM;


base-commit: db2ddb87143519e20a95aa36c60b36107b736a58
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2026-08-26  8:17 [PATCH RFC v2] HID: amd_sfh: Validate PCI BAR size before mapping syzbot
2026-08-26  9:19 ` Slawomir Stepien

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