In the Linux kernel, the following vulnerability has been resolved:
io_uring/sqpoll: zero sqd->thread on tctx errors
Syzkeller reports:
BUG: KASAN: slab-use-after-free in threadgroupcputime+0x409/0x700 kernel/sched/cputime.c:341 Read of size 8 at addr ffff88803578c510 by task syz.2.3223/27552 Call Trace: <TASK> ... kasanreport+0x143/0x180 mm/kasan/report.c:602 threadgroupcputime+0x409/0x700 kernel/sched/cputime.c:341 threadgroupcputimeadjusted+0xa6/0x340 kernel/sched/cputime.c:639 getrusage+0x1000/0x1340 kernel/sys.c:1863 iouringshowfdinfo+0xdfe/0x1770 iouring/fdinfo.c:197 seq_show+0x608/0x770 fs/proc/fd.c:68 ...
That's due to sqd->task not being cleared properly in cases where SQPOLL task tctx setup fails, which can essentially only happen with fault injection to insert allocation errors.