CVE-2026-81009
io_uring/query: cap user size passed to copy_struct_to_user
In the Linux kernel, the following vulnerability has been resolved: io_uring/query: cap user size passed to copy_struct_to_user io_handle_query_entry() clamps hdr.size for the inbound copy_from_user() but keeps the original user value as usize. copy_struct_to_user() uses that usize and, when it is larger than the kernel result, clear_user()s the trailing bytes. As hdr.size is a __u32, a query can request nearly 4 GiB of zeroing, including on the error path where res_size stays 0. The interface is reachable without a ring via IORING_REGISTER_QUERY. Reject sizes larger than PAGE_SIZE, as recommended for copy_struct_* interfaces.
| Vendor | linux |
| Product | linux |
| Ecosystems | |
| Industries | Technology |
| Published | Sep 11, 2026 |
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