io_uring/futex: ensure io_futex_wait() cleans up properly on failure

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: io_uring/futex: ensure io_futex_wait() cleans up properly on failure The io_futex_data is allocated upfront and assigned to the io_kiocb async_data field, but the request isn't marked with REQ_F_ASYNC_DATA at that point. Those two should always go together, as the flag tells io_uring whether the field is valid or not. Additionally, on failure cleanup, the futex handler frees the data but does not clear ->async_data. Clear the data and the flag in the error path as well. Thanks to Trend Micro Zero Day Initiative and particularly ReDress for reporting this.

References

• https://git.kernel.org/stable/c/d9f93172820a53ab42c4b0e5e65291f4f9d00ad2
• https://git.kernel.org/stable/c/d34c04152df517c59979b4bf2a47f491e06d3256
• https://git.kernel.org/stable/c/508c1314b342b78591f51c4b5dadee31a88335df
• https://www.zerodayinitiative.com/advisories/ZDI-25-915/