Re: [syzbot] [fs?] KASAN: slab-use-after-free Read in sys_io_cancel

[Edward Adam Davis]

please test uaf in sys_io_cancel

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master


diff --git a/fs/aio.c b/fs/aio.c
index 28223f511931..38c556514198 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1762,6 +1762,8 @@ static void aio_poll_complete_work(struct work_struct *work)
 	} /* else, POLLFREE has freed the waitqueue, so we must complete */
 	list_del_init(&iocb->ki_list);
 	iocb->ki_res.res = mangle_poll(mask);
+	if (refcount_read(&iocb->ki_refcnt) == 1)
+		iocb->ki_res.obj = -EINVAL;
 	spin_unlock_irq(&ctx->ctx_lock);
 
 	iocb_put(iocb);