Merge tag 'io_uring-5.19-2022-07-21' of git://git.kernel.dk/linux-block

Pull io_uring fixes from Jens Axboe:
 "Fix for a bad kfree() introduced in this cycle, and a quick fix for
  disabling buffer recycling for IORING_OP_READV.

  The latter will get reworked for 5.20, but it gets the job done for
  5.19"

* tag 'io_uring-5.19-2022-07-21' of git://git.kernel.dk/linux-block:
  io_uring: do not recycle buffer in READV
  io_uring: fix free of unallocated buffer list

Author: torvalds

fs/io_uring.c

@@ -1737,6 +1737,14 @@ static void io_kbuf_recycle(struct io_kiocb *req, unsigned issue_flags)
 	    (req->flags & REQ_F_PARTIAL_IO))
 		return;
 
+	/*
+	 * READV uses fields in `struct io_rw` (len/addr) to stash the selected
+	 * buffer data. However if that buffer is recycled the original request
+	 * data stored in addr is lost. Therefore forbid recycling for now.
+	 */
+	if (req->opcode == IORING_OP_READV)
+		return;
+
 	/*
 	 * We don't need to recycle for REQ_F_BUFFER_RING, we can just clear
 	 * the flag and hence ensure that bl->head doesn't get incremented.
@@ -12931,7 +12939,7 @@ static int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
 {
 	struct io_uring_buf_ring *br;
 	struct io_uring_buf_reg reg;
-	struct io_buffer_list *bl;
+	struct io_buffer_list *bl, *free_bl = NULL;
 	struct page **pages;
 	int nr_pages;
 
@@ -12963,7 +12971,7 @@ static int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
 		if (bl->buf_nr_pages || !list_empty(&bl->buf_list))
 			return -EEXIST;
 	} else {
-		bl = kzalloc(sizeof(*bl), GFP_KERNEL);
+		free_bl = bl = kzalloc(sizeof(*bl), GFP_KERNEL);
 		if (!bl)
 			return -ENOMEM;
 	}
@@ -12972,7 +12980,7 @@ static int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
 			     struct_size(br, bufs, reg.ring_entries),
 			     &nr_pages);
 	if (IS_ERR(pages)) {
-		kfree(bl);
+		kfree(free_bl);
 		return PTR_ERR(pages);
 	}