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iommu/vt-d: Fix NULL pointer dereference in dev_iommu_priv_set()
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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: 01b9d4e ("iommu/vt-d: Use dev_iommu_priv_get/set()")
Reported-by: Torsten Hilbrich <[email protected]>
Reported-by: Wendy Wang <[email protected]>
Signed-off-by: Lu Baolu <[email protected]>
Tested-by: Torsten Hilbrich <[email protected]>
Link: https://lore.kernel.org/linux-iommu/[email protected]/
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Joerg Roedel <[email protected]>
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@LuBaolu @joergroedel
LuBaolu authored and joergroedel committed Sep 4, 2020
1 parent 6e4e9ec commit 2d33b7d
Showing 1 changed file with 55 additions and 45 deletions.
100 changes: 55 additions & 45 deletions drivers/iommu/intel/iommu.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)
{
Expand All @@ -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;
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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;
Expand All @@ -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)) {
Expand All @@ -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;

Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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 */
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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);
}
}
}

Expand Down

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