iommufd: Fix struct iommu_hwpt_pgfault init and padding
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>
e721f619e3