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Subject[PATCH 3.18 099/124] iommu/vt-d: Fix NULL pointer dereference in device_to_iommu
Date
3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Koos Vriezen <koos.vriezen@gmail.com>

commit 5003ae1e735e6bfe4679d9bed6846274f322e77e upstream.

The function device_to_iommu() in the Intel VT-d driver
lacks a NULL-ptr check, resulting in this oops at boot on
some platforms:

BUG: unable to handle kernel NULL pointer dereference at 00000000000007ab
IP: [<ffffffff8132234a>] device_to_iommu+0x11a/0x1a0
PGD 0

[...]

Call Trace:
? find_or_alloc_domain.constprop.29+0x1a/0x300
? dw_dma_probe+0x561/0x580 [dw_dmac_core]
? __get_valid_domain_for_dev+0x39/0x120
? __intel_map_single+0x138/0x180
? intel_alloc_coherent+0xb6/0x120
? sst_hsw_dsp_init+0x173/0x420 [snd_soc_sst_haswell_pcm]
? mutex_lock+0x9/0x30
? kernfs_add_one+0xdb/0x130
? devres_add+0x19/0x60
? hsw_pcm_dev_probe+0x46/0xd0 [snd_soc_sst_haswell_pcm]
? platform_drv_probe+0x30/0x90
? driver_probe_device+0x1ed/0x2b0
? __driver_attach+0x8f/0xa0
? driver_probe_device+0x2b0/0x2b0
? bus_for_each_dev+0x55/0x90
? bus_add_driver+0x110/0x210
? 0xffffffffa11ea000
? driver_register+0x52/0xc0
? 0xffffffffa11ea000
? do_one_initcall+0x32/0x130
? free_vmap_area_noflush+0x37/0x70
? kmem_cache_alloc+0x88/0xd0
? do_init_module+0x51/0x1c4
? load_module+0x1ee9/0x2430
? show_taint+0x20/0x20
? kernel_read_file+0xfd/0x190
? SyS_finit_module+0xa3/0xb0
? do_syscall_64+0x4a/0xb0
? entry_SYSCALL64_slow_path+0x25/0x25
Code: 78 ff ff ff 4d 85 c0 74 ee 49 8b 5a 10 0f b6 9b e0 00 00 00 41 38 98 e0 00 00 00 77 da 0f b6 eb 49 39 a8 88 00 00 00 72 ce eb 8f <41> f6 82 ab 07 00 00 04 0f 85 76 ff ff ff 0f b6 4d 08 88 0e 49
RIP [<ffffffff8132234a>] device_to_iommu+0x11a/0x1a0
RSP <ffffc90001457a78>
CR2: 00000000000007ab
---[ end trace 16f974b6d58d0aad ]---

Add the missing pointer check.

Fixes: 1c387188c60f53b338c20eee32db055dfe022a9b ("iommu/vt-d: Fix IOMMU lookup for SR-IOV Virtual Functions")
Signed-off-by: Koos Vriezen <koos.vriezen@gmail.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/iommu/intel-iommu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -719,7 +719,7 @@ static struct intel_iommu *device_to_iom
* which we used for the IOMMU lookup. Strictly speaking
* we could do this for all PCI devices; we only need to
* get the BDF# from the scope table for ACPI matches. */
- if (pdev->is_virtfn)
+ if (pdev && pdev->is_virtfn)
goto got_pdev;

*bus = drhd->devices[i].bus;

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