Affected: Alpaquita:25: linux-lts, Alpaquita:stream: linux-lts

In the Linux kernel, the following vulnerability has been resolved:

iommu/tegra241-cmdqv: Publish an LVCMDQ only after it is fully initialized

tegra241_vintf_init_lvcmdq() stores the freshly allocated vcmdq pointer to the vintf->lvcmdqs[] array, before tegra241_vcmdq_alloc_smmu_cmdq() builds the vcmdq->cmdq. The error ISR dereferences that cmdq, so a latched LVCMDQ error (e.g. one inherited across a kexec) firing in this window would make tegra241_vintf0_handle_error() pass the still-zeroed arm_smmu_cmdq down to __arm_smmu_cmdq_skip_err(), dereferencing NULL queue register pointers.

Drop the store from tegra241_vintf_init_lvcmdq() and publish the vcmdq at the end of the allocation instead, with an smp_store_release() that pairs with an smp_load_acquire() in the ISR, which can see a fully built LVCMDQ or NULL.

The user-owned LVCMDQ allocation moves accordingly, publishing the vcmdq once tegra241_vcmdq_hw_init_user() succeeds, using a plain store since a user VINTF's lvcmdqs[] has no lockless reader -- the error ISR only walks the VINTF0 array.

In the Linux kernel, the following vulnerability has been resolved:

iommu/tegra241-cmdqv: Publish an LVCMDQ only after it is fully initialized

tegra241_vintf_init_lvcmdq() stores the freshly allocated vcmdq pointer to the vintf->lvcmdqs[] array, before tegra241_vcmdq_alloc_smmu_cmdq() builds the vcmdq->cmdq. The error ISR dereferences that cmdq, so a latched LVCMDQ error (e.g. one inherited across a kexec) firing in this window would make tegra241_vintf0_handle_error() pass the still-zeroed arm_smmu_cmdq down to __arm_smmu_cmdq_skip_err(), dereferencing NULL queue register pointers.

Drop the store from tegra241_vintf_init_lvcmdq() and publish the vcmdq at the end of the allocation instead, with an smp_store_release() that pairs with an smp_load_acquire() in the ISR, which can see a fully built LVCMDQ or NULL.

The user-owned LVCMDQ allocation moves accordingly, publishing the vcmdq once tegra241_vcmdq_hw_init_user() succeeds, using a plain store since a user VINTF's lvcmdqs[] has no lockless reader -- the error ISR only walks the VINTF0 array.

kernel-devel-7.2.8-1.1 on GA media

Affected: Ubuntu:16.04:LTS: linux-hwe-edge, Ubuntu:18.04:LTS: linux-aws-5.0, Ubuntu:18.04:LTS: linux-aws-5.3, Ubuntu:18.04:LTS: linux-azure, Ubuntu:18.04:LTS: linux-azure-5.3, Ubuntu:18.04:LTS: linux-azure-edge, Ubuntu:18.04:LTS: linux-gcp, Ubuntu:18.04:LTS: linux-gcp-5.3, Ubuntu:18.04:LTS: linux-gke-4.15, Ubuntu:18.04:LTS: linux-gke-5.4 and 125 more

In the Linux kernel, the following vulnerability has been resolved: iommu/tegra241-cmdqv: Publish an LVCMDQ only after it is fully initialized tegra241_vintf_init_lvcmdq() stores the freshly allocated vcmdq pointer to the vintf->lvcmdqs[] array, before tegra241_vcmdq_alloc_smmu_cmdq() builds the vcmdq->cmdq. The error ISR dereferences that cmdq, so a latched LVCMDQ error (e.g. one inherited across a kexec) firing in this window would make tegra241_vintf0_handle_error() pass the still-zeroed arm_smmu_cmdq down to __arm_smmu_cmdq_skip_err(), dereferencing NULL queue register pointers. Drop the store from tegra241_vintf_init_lvcmdq() and publish the vcmdq at the end of the allocation instead, with an smp_store_release() that pairs with an smp_load_acquire() in the ISR, which can see a fully built LVCMDQ or NULL. The user-owned LVCMDQ allocation moves accordingly, publishing the vcmdq once tegra241_vcmdq_hw_init_user() succeeds, using a plain store since a user VINTF's lvcmdqs[] has no lockless reader -- the error ISR only walks the VINTF0 array.