| From aff8c8242bc638ba57247ae1ec5f272ac3ed3b92 Mon Sep 17 00:00:00 2001 |
| From: Tyrel Datwyler <tyreld@linux.vnet.ibm.com> |
| Date: Mon, 20 Jan 2020 14:10:02 -0800 |
| Subject: powerpc/pseries/vio: Fix iommu_table use-after-free refcount warning |
| |
| From: Tyrel Datwyler <tyreld@linux.vnet.ibm.com> |
| |
| commit aff8c8242bc638ba57247ae1ec5f272ac3ed3b92 upstream. |
| |
| 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> |
| Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru> |
| Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> |
| Link: https://lore.kernel.org/r/1579558202-26052-1-git-send-email-tyreld@linux.ibm.com |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/powerpc/platforms/pseries/vio.c | 2 ++ |
| 1 file changed, 2 insertions(+) |
| |
| --- a/arch/powerpc/platforms/pseries/vio.c |
| +++ b/arch/powerpc/platforms/pseries/vio.c |
| @@ -1176,6 +1176,8 @@ static struct iommu_table *vio_build_iom |
| 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); |
| |
