If we use IORING_OP_RECV with provided buffers and pass in '0' as the
length of the request, the length is retrieved from the selected buffer.
If MSG_WAITALL is also set and we get a short receive, then we may hit
the retry path which decrements sr->len and increments the buffer for
a retry. However, the length is still zero at this point, which means
that sr->len now becomes huge and import_ubuf() will cap it to
MAX_RW_COUNT and subsequently return -EFAULT for the range as a whole.
Fix this by always assigning sr->len once the buffer has been selected.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 7ba89d2af17a ("io_uring: ensure recv and recvmsg handle MSG_WAITALL correctly")
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
diff --git a/io_uring/net.c b/io_uring/net.c
index a12ff69e6843..43bc9a5f96f9 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -923,6 +923,7 @@ int io_recv(struct io_kiocb *req, unsigned int issue_flags)
if (!buf)
return -ENOBUFS;
sr->buf = buf;
+ sr->len = len;
}
ret = import_ubuf(ITER_DEST, sr->buf, len, &msg.msg_iter);
--
Jens Axboe
