From: Tyrel Datwyler <tyreld@linux.ibm.com>
To: mpe@ellerman.id.au
Cc: Tyrel Datwyler <tyreld@linux.ibm.com>,
aik@ozlabs.ru, Tyrel Datwyler <tyreld@linux.vnet.ibm.com>,
drt@linux.ibm.com, linuxppc-dev@lists.ozlabs.org,
david@gibson.dropbear.id.au
Subject: [PATCH] powerpc/pseries/vio: Fix iommu_table use-after-free refcount warning
Date: Mon, 20 Jan 2020 14:10:02 -0800 [thread overview]
Message-ID: <1579558202-26052-1-git-send-email-tyreld@linux.ibm.com> (raw)
From: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Commit e5afdf9dd515 ("powerpc/vfio_spapr_tce: Add reference counting to
iommu_table") missed an iommu_table allocation in the pseries vio code.
The iommu_table is allocated with kzalloc and as a result the associated
kref gets a value of zero. This has the side effect that during a DLPAR
remove of the associated virtual IOA the iommu_tce_table_put() triggers
a use-after-free underflow warning.
Call Trace:
[c0000002879e39f0] [c00000000071ecb4] refcount_warn_saturate+0x184/0x190
(unreliable)
[c0000002879e3a50] [c0000000000500ac] iommu_tce_table_put+0x9c/0xb0
[c0000002879e3a70] [c0000000000f54e4] vio_dev_release+0x34/0x70
[c0000002879e3aa0] [c00000000087cfa4] device_release+0x54/0xf0
[c0000002879e3b10] [c000000000d64c84] kobject_cleanup+0xa4/0x240
[c0000002879e3b90] [c00000000087d358] put_device+0x28/0x40
[c0000002879e3bb0] [c0000000007a328c] dlpar_remove_slot+0x15c/0x250
[c0000002879e3c50] [c0000000007a348c] remove_slot_store+0xac/0xf0
[c0000002879e3cd0] [c000000000d64220] kobj_attr_store+0x30/0x60
[c0000002879e3cf0] [c0000000004ff13c] sysfs_kf_write+0x6c/0xa0
[c0000002879e3d10] [c0000000004fde4c] kernfs_fop_write+0x18c/0x260
[c0000002879e3d60] [c000000000410f3c] __vfs_write+0x3c/0x70
[c0000002879e3d80] [c000000000415408] vfs_write+0xc8/0x250
[c0000002879e3dd0] [c0000000004157dc] ksys_write+0x7c/0x120
[c0000002879e3e20] [c00000000000b278] system_call+0x5c/0x68
Further, since the refcount was always zero the iommu_tce_table_put()
fails to call the iommu_table release function resulting in a leak.
Fix this issue be initilizing the iommu_table kref immediately after
allocation.
Fixes: e5afdf9dd515 ("powerpc/vfio_spapr_tce: Add reference counting to iommu_table")
Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
---
arch/powerpc/platforms/pseries/vio.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/powerpc/platforms/pseries/vio.c b/arch/powerpc/platforms/pseries/vio.c
index 79e2287..f682b7b 100644
--- a/arch/powerpc/platforms/pseries/vio.c
+++ b/arch/powerpc/platforms/pseries/vio.c
@@ -1176,6 +1176,8 @@ static struct iommu_table *vio_build_iommu_table(struct vio_dev *dev)
if (tbl == NULL)
return NULL;
+ kref_init(&tbl->it_kref);
+
of_parse_dma_window(dev->dev.of_node, dma_window,
&tbl->it_index, &offset, &size);
--
1.8.3.1
next reply other threads:[~2020-01-20 22:12 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-20 22:10 Tyrel Datwyler [this message]
2020-01-21 3:45 ` [PATCH] powerpc/pseries/vio: Fix iommu_table use-after-free refcount warning Alexey Kardashevskiy
2020-01-29 5:17 ` Michael Ellerman
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