On Mon, 2020-01-20 at 22:10:02 UTC, Tyrel Datwyler wrote: > From: Tyrel Datwyler <tyr...@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 <tyr...@linux.ibm.com>
Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/aff8c8242bc638ba57247ae1ec5f272ac3ed3b92 cheers