From cffaaf0c816238c45cd2d06913476c83eb50f682 Mon Sep 17 00:00:00 2001
From: Julia Cartwright <julia@ni.com>
Date: Wed, 20 Feb 2019 16:46:31 +0000
Subject: iommu/dmar: Fix buffer overflow during PCI bus notification

Commit 57384592c433 ("iommu/vt-d: Store bus information in RMRR PCI
device path") changed the type of the path data, however, the change in
path type was not reflected in size calculations.  Update to use the
correct type and prevent a buffer overflow.

This bug manifests in systems with deep PCI hierarchies, and can lead to
an overflow of the static allocated buffer (dmar_pci_notify_info_buf),
or can lead to overflow of slab-allocated data.

   BUG: KASAN: global-out-of-bounds in dmar_alloc_pci_notify_info+0x1d5/0x2e0
   Write of size 1 at addr ffffffff90445d80 by task swapper/0/1
   CPU: 0 PID: 1 Comm: swapper/0 Tainted: G        W       4.14.87-rt49-02406-gd0a0e96 #1
   Call Trace:
    ? dump_stack+0x46/0x59
    ? print_address_description+0x1df/0x290
    ? dmar_alloc_pci_notify_info+0x1d5/0x2e0
    ? kasan_report+0x256/0x340
    ? dmar_alloc_pci_notify_info+0x1d5/0x2e0
    ? e820__memblock_setup+0xb0/0xb0
    ? dmar_dev_scope_init+0x424/0x48f
    ? __down_write_common+0x1ec/0x230
    ? dmar_dev_scope_init+0x48f/0x48f
    ? dmar_free_unused_resources+0x109/0x109
    ? cpumask_next+0x16/0x20
    ? __kmem_cache_create+0x392/0x430
    ? kmem_cache_create+0x135/0x2f0
    ? e820__memblock_setup+0xb0/0xb0
    ? intel_iommu_init+0x170/0x1848
    ? _raw_spin_unlock_irqrestore+0x32/0x60
    ? migrate_enable+0x27a/0x5b0
    ? sched_setattr+0x20/0x20
    ? migrate_disable+0x1fc/0x380
    ? task_rq_lock+0x170/0x170
    ? try_to_run_init_process+0x40/0x40
    ? locks_remove_file+0x85/0x2f0
    ? dev_prepare_static_identity_mapping+0x78/0x78
    ? rt_spin_unlock+0x39/0x50
    ? lockref_put_or_lock+0x2a/0x40
    ? dput+0x128/0x2f0
    ? __rcu_read_unlock+0x66/0x80
    ? __fput+0x250/0x300
    ? __rcu_read_lock+0x1b/0x30
    ? mntput_no_expire+0x38/0x290
    ? e820__memblock_setup+0xb0/0xb0
    ? pci_iommu_init+0x25/0x63
    ? pci_iommu_init+0x25/0x63
    ? do_one_initcall+0x7e/0x1c0
    ? initcall_blacklisted+0x120/0x120
    ? kernel_init_freeable+0x27b/0x307
    ? rest_init+0xd0/0xd0
    ? kernel_init+0xf/0x120
    ? rest_init+0xd0/0xd0
    ? ret_from_fork+0x1f/0x40
   The buggy address belongs to the variable:
    dmar_pci_notify_info_buf+0x40/0x60

Fixes: 57384592c433 ("iommu/vt-d: Store bus information in RMRR PCI device path")
Signed-off-by: Julia Cartwright <julia@ni.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 drivers/iommu/dmar.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index dc9f14811e0f..58dc70bffd5b 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -144,7 +144,7 @@ dmar_alloc_pci_notify_info(struct pci_dev *dev, unsigned long event)
 		for (tmp = dev; tmp; tmp = tmp->bus->self)
 			level++;
 
-	size = sizeof(*info) + level * sizeof(struct acpi_dmar_pci_path);
+	size = sizeof(*info) + level * sizeof(info->path[0]);
 	if (size <= sizeof(dmar_pci_notify_info_buf)) {
 		info = (struct dmar_pci_notify_info *)dmar_pci_notify_info_buf;
 	} else {
-- 
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