From: Pratyush Brahma <quic_pbrahma@quicinc.com> stable inclusion from stable-v5.10.231 commit c2527d07c7e9cda2c6165d5edccf74752baac1b0 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBEAME CVE: CVE-2024-56568 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 229e6ee43d2a160a1592b83aad620d6027084aad upstream. Null pointer dereference occurs due to a race between smmu driver probe and client driver probe, when of_dma_configure() for client is called after the iommu_device_register() for smmu driver probe has executed but before the driver_bound() for smmu driver has been called. Following is how the race occurs: T1:Smmu device probe T2: Client device probe really_probe() arm_smmu_device_probe() iommu_device_register() really_probe() platform_dma_configure() of_dma_configure() of_dma_configure_id() of_iommu_configure() iommu_probe_device() iommu_init_device() arm_smmu_probe_device() arm_smmu_get_by_fwnode() driver_find_device_by_fwnode() driver_find_device() next_device() klist_next() /* null ptr assigned to smmu */ /* null ptr dereference while smmu->streamid_mask */ driver_bound() klist_add_tail() When this null smmu pointer is dereferenced later in arm_smmu_probe_device, the device crashes. Fix this by deferring the probe of the client device until the smmu device has bound to the arm smmu driver. Fixes: 021bb8420d44 ("iommu/arm-smmu: Wire up generic configuration support") Cc: stable@vger.kernel.org Co-developed-by: Prakash Gupta <quic_guptap@quicinc.com> Signed-off-by: Prakash Gupta <quic_guptap@quicinc.com> Signed-off-by: Pratyush Brahma <quic_pbrahma@quicinc.com> Link: https://lore.kernel.org/r/20241004090428.2035-1-quic_pbrahma@quicinc.com [will: Add comment] Signed-off-by: Will Deacon <will@kernel.org> [rm: backport for context conflict prior to 6.8] Signed-off-by: Robin Murphy <robin.murphy@arm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Zhang Zekun <zhangzekun11@huawei.com> --- drivers/iommu/arm/arm-smmu/arm-smmu.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c index b57536b024ac..39cc38876d87 100644 --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c @@ -1372,6 +1372,17 @@ static struct iommu_device *arm_smmu_probe_device(struct device *dev) goto out_free; } else if (fwspec && fwspec->ops == &arm_smmu_ops) { smmu = arm_smmu_get_by_fwnode(fwspec->iommu_fwnode); + + /* + * Defer probe if the relevant SMMU instance hasn't finished + * probing yet. This is a fragile hack and we'd ideally + * avoid this race in the core code. Until that's ironed + * out, however, this is the most pragmatic option on the + * table. + */ + if (!smmu) + return ERR_PTR(dev_err_probe(dev, -EPROBE_DEFER, + "smmu dev has not bound yet\n")); } else { return ERR_PTR(-ENODEV); } -- 2.22.0