In the Linux kernel, the following vulnerability has been resolved:io_uring/tctx: work around xa_store() allocation error issuesyzbot triggered the following WARN_ON:WARNING: CPU: 0 PID: 16 at io_uring/tctx.c:51 __io_uring_free+0xfa/0x140 io_uring/tctx.c:51which is theWARN_ON_ONCE(!xa_empty(&tctx->xa));sanity check in __io_uring_free() when a io_uring_task is going throughits final put. The syzbot test case includes injecting memory allocationfailures, and it very much looks like xa_store() can fail one of itsmemory allocations and end up with ->head being non-NULL even though noentries exist in the xarray.Until this issue gets sorted out, work around it by attempting toiterate entries in our xarray, and WARN_ON_ONCE() if one is found.
