From 2d33b7d631d9dc81c78bb71368645cf7f0e68cb1 Mon Sep 17 00:00:00 2001 From: Lu Baolu Date: Thu, 3 Sep 2020 14:51:32 +0800 Subject: [PATCH] iommu/vt-d: Fix NULL pointer dereference in dev_iommu_priv_set() The dev_iommu_priv_set() must be called after probe_device(). This fixes a NULL pointer deference bug when booting a system with kernel cmdline "intel_iommu=on,igfx_off", where the dev_iommu_priv_set() is abused. The following stacktrace was produced: Command line: BOOT_IMAGE=/isolinux/bzImage console=tty1 intel_iommu=on,igfx_off ... DMAR: Host address width 39 DMAR: DRHD base: 0x000000fed90000 flags: 0x0 DMAR: dmar0: reg_base_addr fed90000 ver 1:0 cap 1c0000c40660462 ecap 19e2ff0505e DMAR: DRHD base: 0x000000fed91000 flags: 0x1 DMAR: dmar1: reg_base_addr fed91000 ver 1:0 cap d2008c40660462 ecap f050da DMAR: RMRR base: 0x0000009aa9f000 end: 0x0000009aabefff DMAR: RMRR base: 0x0000009d000000 end: 0x0000009f7fffff DMAR: No ATSR found BUG: kernel NULL pointer dereference, address: 0000000000000038 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 0 P4D 0 Oops: 0002 [#1] SMP PTI CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.9.0-devel+ #2 Hardware name: LENOVO 20HGS0TW00/20HGS0TW00, BIOS N1WET46S (1.25s ) 03/30/2018 RIP: 0010:intel_iommu_init+0xed0/0x1136 Code: fe e9 61 02 00 00 bb f4 ff ff ff e9 57 02 00 00 48 63 d1 48 c1 e2 04 48 03 50 20 48 8b 12 48 85 d2 74 0b 48 8b 92 d0 02 00 00 48 89 7a 38 ff c1 e9 15 f5 ff ff 48 c7 c7 60 99 ac a7 49 c7 c7 a0 RSP: 0000:ffff96d180073dd0 EFLAGS: 00010282 RAX: ffff8c91037a7d20 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffffffffffff RBP: ffff96d180073e90 R08: 0000000000000001 R09: ffff8c91039fe3c0 R10: 0000000000000226 R11: 0000000000000226 R12: 000000000000000b R13: ffff8c910367c650 R14: ffffffffa8426d60 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8c9107480000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000038 CR3: 00000004b100a001 CR4: 00000000003706e0 Call Trace: ? _raw_spin_unlock_irqrestore+0x1f/0x30 ? call_rcu+0x10e/0x320 ? trace_hardirqs_on+0x2c/0xd0 ? rdinit_setup+0x2c/0x2c ? e820__memblock_setup+0x8b/0x8b pci_iommu_init+0x16/0x3f do_one_initcall+0x46/0x1e4 kernel_init_freeable+0x169/0x1b2 ? rest_init+0x9f/0x9f kernel_init+0xa/0x101 ret_from_fork+0x22/0x30 Modules linked in: CR2: 0000000000000038 ---[ end trace 3653722a6f936f18 ]--- Fixes: 01b9d4e21148c ("iommu/vt-d: Use dev_iommu_priv_get/set()") Reported-by: Torsten Hilbrich Reported-by: Wendy Wang Signed-off-by: Lu Baolu Tested-by: Torsten Hilbrich Link: https://lore.kernel.org/linux-iommu/96717683-70be-7388-3d2f-61131070a96a@secunet.com/ Link: https://lore.kernel.org/r/20200903065132.16879-1-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel --- drivers/iommu/intel/iommu.c | 100 ++++++++++++++++++++---------------- 1 file changed, 55 insertions(+), 45 deletions(-) diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index f8177c59d229a..acd537294c926 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -364,7 +364,6 @@ static int iommu_skip_te_disable; int intel_iommu_gfx_mapped; EXPORT_SYMBOL_GPL(intel_iommu_gfx_mapped); -#define DUMMY_DEVICE_DOMAIN_INFO ((struct device_domain_info *)(-1)) #define DEFER_DEVICE_DOMAIN_INFO ((struct device_domain_info *)(-2)) struct device_domain_info *get_domain_info(struct device *dev) { @@ -374,8 +373,7 @@ struct device_domain_info *get_domain_info(struct device *dev) return NULL; info = dev_iommu_priv_get(dev); - if (unlikely(info == DUMMY_DEVICE_DOMAIN_INFO || - info == DEFER_DEVICE_DOMAIN_INFO)) + if (unlikely(info == DEFER_DEVICE_DOMAIN_INFO)) return NULL; return info; @@ -742,11 +740,6 @@ struct context_entry *iommu_context_addr(struct intel_iommu *iommu, u8 bus, return &context[devfn]; } -static int iommu_dummy(struct device *dev) -{ - return dev_iommu_priv_get(dev) == DUMMY_DEVICE_DOMAIN_INFO; -} - static bool attach_deferred(struct device *dev) { return dev_iommu_priv_get(dev) == DEFER_DEVICE_DOMAIN_INFO; @@ -779,6 +772,53 @@ is_downstream_to_pci_bridge(struct device *dev, struct device *bridge) return false; } +static bool quirk_ioat_snb_local_iommu(struct pci_dev *pdev) +{ + struct dmar_drhd_unit *drhd; + u32 vtbar; + int rc; + + /* We know that this device on this chipset has its own IOMMU. + * If we find it under a different IOMMU, then the BIOS is lying + * to us. Hope that the IOMMU for this device is actually + * disabled, and it needs no translation... + */ + rc = pci_bus_read_config_dword(pdev->bus, PCI_DEVFN(0, 0), 0xb0, &vtbar); + if (rc) { + /* "can't" happen */ + dev_info(&pdev->dev, "failed to run vt-d quirk\n"); + return false; + } + vtbar &= 0xffff0000; + + /* we know that the this iommu should be at offset 0xa000 from vtbar */ + drhd = dmar_find_matched_drhd_unit(pdev); + if (!drhd || drhd->reg_base_addr - vtbar != 0xa000) { + pr_warn_once(FW_BUG "BIOS assigned incorrect VT-d unit for Intel(R) QuickData Technology device\n"); + add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_STILL_OK); + return true; + } + + return false; +} + +static bool iommu_is_dummy(struct intel_iommu *iommu, struct device *dev) +{ + if (!iommu || iommu->drhd->ignored) + return true; + + if (dev_is_pci(dev)) { + struct pci_dev *pdev = to_pci_dev(dev); + + if (pdev->vendor == PCI_VENDOR_ID_INTEL && + pdev->device == PCI_DEVICE_ID_INTEL_IOAT_SNB && + quirk_ioat_snb_local_iommu(pdev)) + return true; + } + + return false; +} + struct intel_iommu *device_to_iommu(struct device *dev, u8 *bus, u8 *devfn) { struct dmar_drhd_unit *drhd = NULL; @@ -788,7 +828,7 @@ struct intel_iommu *device_to_iommu(struct device *dev, u8 *bus, u8 *devfn) u16 segment = 0; int i; - if (!dev || iommu_dummy(dev)) + if (!dev) return NULL; if (dev_is_pci(dev)) { @@ -805,7 +845,7 @@ struct intel_iommu *device_to_iommu(struct device *dev, u8 *bus, u8 *devfn) dev = &ACPI_COMPANION(dev)->dev; rcu_read_lock(); - for_each_active_iommu(iommu, drhd) { + for_each_iommu(iommu, drhd) { if (pdev && segment != drhd->segment) continue; @@ -841,6 +881,9 @@ struct intel_iommu *device_to_iommu(struct device *dev, u8 *bus, u8 *devfn) } iommu = NULL; out: + if (iommu_is_dummy(iommu, dev)) + iommu = NULL; + rcu_read_unlock(); return iommu; @@ -2447,7 +2490,7 @@ struct dmar_domain *find_domain(struct device *dev) { struct device_domain_info *info; - if (unlikely(attach_deferred(dev) || iommu_dummy(dev))) + if (unlikely(attach_deferred(dev))) return NULL; /* No lock here, assumes no domain exit in normal case */ @@ -3989,35 +4032,6 @@ static void __init iommu_exit_mempool(void) iova_cache_put(); } -static void quirk_ioat_snb_local_iommu(struct pci_dev *pdev) -{ - struct dmar_drhd_unit *drhd; - u32 vtbar; - int rc; - - /* We know that this device on this chipset has its own IOMMU. - * If we find it under a different IOMMU, then the BIOS is lying - * to us. Hope that the IOMMU for this device is actually - * disabled, and it needs no translation... - */ - rc = pci_bus_read_config_dword(pdev->bus, PCI_DEVFN(0, 0), 0xb0, &vtbar); - if (rc) { - /* "can't" happen */ - dev_info(&pdev->dev, "failed to run vt-d quirk\n"); - return; - } - vtbar &= 0xffff0000; - - /* we know that the this iommu should be at offset 0xa000 from vtbar */ - drhd = dmar_find_matched_drhd_unit(pdev); - if (!drhd || drhd->reg_base_addr - vtbar != 0xa000) { - pr_warn_once(FW_BUG "BIOS assigned incorrect VT-d unit for Intel(R) QuickData Technology device\n"); - add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_STILL_OK); - dev_iommu_priv_set(&pdev->dev, DUMMY_DEVICE_DOMAIN_INFO); - } -} -DECLARE_PCI_FIXUP_ENABLE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_IOAT_SNB, quirk_ioat_snb_local_iommu); - static void __init init_no_remapping_devices(void) { struct dmar_drhd_unit *drhd; @@ -4049,12 +4063,8 @@ static void __init init_no_remapping_devices(void) /* This IOMMU has *only* gfx devices. Either bypass it or set the gfx_mapped flag, as appropriate */ drhd->gfx_dedicated = 1; - if (!dmar_map_gfx) { + if (!dmar_map_gfx) drhd->ignored = 1; - for_each_active_dev_scope(drhd->devices, - drhd->devices_cnt, i, dev) - dev_iommu_priv_set(dev, DUMMY_DEVICE_DOMAIN_INFO); - } } }