6.12-stable review patch. If anyone has any objections, please let me know.
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From: Nicolin Chen nicolinc@nvidia.com
commit e721f619e3ec9bae08bf419c3944cf1e6966c821 upstream.
The iommu_hwpt_pgfault is used to report IO page fault data to userspace, but iommufd_fault_fops_read was never zeroing its padding. This leaks the content of the kernel stack memory to userspace.
Also, the iommufd uAPI requires explicit padding and use of __aligned_u64 to ensure ABI compatibility's with 32 bit.
pahole result, before: struct iommu_hwpt_pgfault { __u32 flags; /* 0 4 */ __u32 dev_id; /* 4 4 */ __u32 pasid; /* 8 4 */ __u32 grpid; /* 12 4 */ __u32 perm; /* 16 4 */
/* XXX 4 bytes hole, try to pack */
__u64 addr; /* 24 8 */ __u32 length; /* 32 4 */ __u32 cookie; /* 36 4 */
/* size: 40, cachelines: 1, members: 8 */ /* sum members: 36, holes: 1, sum holes: 4 */ /* last cacheline: 40 bytes */ };
pahole result, after: struct iommu_hwpt_pgfault { __u32 flags; /* 0 4 */ __u32 dev_id; /* 4 4 */ __u32 pasid; /* 8 4 */ __u32 grpid; /* 12 4 */ __u32 perm; /* 16 4 */ __u32 __reserved; /* 20 4 */ __u64 addr __attribute__((__aligned__(8))); /* 24 8 */ __u32 length; /* 32 4 */ __u32 cookie; /* 36 4 */
/* size: 40, cachelines: 1, members: 9 */ /* forced alignments: 1 */ /* last cacheline: 40 bytes */ } __attribute__((__aligned__(8)));
Fixes: c714f15860fc ("iommufd: Add fault and response message definitions") Link: https://patch.msgid.link/r/20250120195051.2450-1-nicolinc@nvidia.com Cc: stable@vger.kernel.org Reviewed-by: Jason Gunthorpe jgg@nvidia.com Signed-off-by: Nicolin Chen nicolinc@nvidia.com Reviewed-by: Kevin Tian kevin.tian@intel.com Signed-off-by: Jason Gunthorpe jgg@nvidia.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/iommu/iommufd/fault.c | 2 +- include/uapi/linux/iommufd.h | 4 +++- 2 files changed, 4 insertions(+), 2 deletions(-)
--- a/drivers/iommu/iommufd/fault.c +++ b/drivers/iommu/iommufd/fault.c @@ -242,7 +242,7 @@ static ssize_t iommufd_fault_fops_read(s { size_t fault_size = sizeof(struct iommu_hwpt_pgfault); struct iommufd_fault *fault = filep->private_data; - struct iommu_hwpt_pgfault data; + struct iommu_hwpt_pgfault data = {}; struct iommufd_device *idev; struct iopf_group *group; struct iopf_fault *iopf; --- a/include/uapi/linux/iommufd.h +++ b/include/uapi/linux/iommufd.h @@ -737,6 +737,7 @@ enum iommu_hwpt_pgfault_perm { * @pasid: Process Address Space ID * @grpid: Page Request Group Index * @perm: Combination of enum iommu_hwpt_pgfault_perm + * @__reserved: Must be 0. * @addr: Fault address * @length: a hint of how much data the requestor is expecting to fetch. For * example, if the PRI initiator knows it is going to do a 10MB @@ -752,7 +753,8 @@ struct iommu_hwpt_pgfault { __u32 pasid; __u32 grpid; __u32 perm; - __u64 addr; + __u32 __reserved; + __aligned_u64 addr; __u32 length; __u32 cookie; };