Commits
Will Deacon committed e83861a6a05
FROMLIST: iommu/arm-smmu: Prevent forced unbinding of Arm SMMU drivers Forcefully unbinding the Arm SMMU drivers is a pretty dangerous operation, since it will likely lead to catastrophic failure for any DMA devices mastering through the SMMU being unbound. When the driver then attempts to "handle" the fatal faults, it's very easy to trip over dead data structures, leading to use-after-free. On John's machine, he reports that the machine was "unusable" due to loss of the storage controller following a forced unbind of the SMMUv3 driver: | # cd ./bus/platform/drivers/arm-smmu-v3 | # echo arm-smmu-v3.0.auto > unbind | hisi_sas_v2_hw HISI0162:01: CQE_AXI_W_ERR (0x800) found! | platform arm-smmu-v3.0.auto: CMD_SYNC timeout at 0x00000146 | [hwprod 0x00000146, hwcons 0x00000000] Prevent this forced unbinding of the drivers by setting "suppress_bind_attrs" to true. Link: https://lore.kernel.org/lkml/06dfd385-1af0-3106-4cc5-6a5b8e864759@huawei.com Reported-by: John Garry <john.garry@huawei.com> Signed-off-by: Will Deacon <will@kernel.org> Bug: 140290589 Link: https://lore.kernel.org/lkml/20191121114918.2293-10-will@kernel.org/ Signed-off-by: Will Deacon <willdeacon@google.com> Change-Id: I8b1c439f7ba11d6fc38cdf686948ef5909871dfb