On Thu, Jan 05, 2023 at 10:04:19AM -0800, Kees Cook wrote:
On Thu, Jan 05, 2023 at 08:39:48AM +0100, Greg KH wrote:
On Wed, Jan 04, 2023 at 07:37:48PM -0800, Kees Cook wrote:
Zero-length arrays are deprecated[1]. Replace struct io_uring_buf_ring's "bufs" with a flexible array member. (How is the size of this array verified?) Detected with GCC 13, using -fstrict-flex-arrays=3:
In function 'io_ring_buffer_select', inlined from 'io_buffer_select' at io_uring/kbuf.c:183:10: io_uring/kbuf.c:141:23: warning: array subscript 255 is outside the bounds of an interior zero-length array 'struct io_uring_buf[0]' [-Wzero-length-bounds] 141 | buf = &br->bufs[head]; | ^~~~~~~~~~~~~~~ In file included from include/linux/io_uring.h:7, from io_uring/kbuf.c:10: include/uapi/linux/io_uring.h: In function 'io_buffer_select': include/uapi/linux/io_uring.h:628:41: note: while referencing 'bufs' 628 | struct io_uring_buf bufs[0]; | ^~~~
[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-a...
Fixes: c7fb19428d67 ("io_uring: add support for ring mapped supplied buffers") Cc: Jens Axboe axboe@kernel.dk Cc: Pavel Begunkov asml.silence@gmail.com Cc: "Gustavo A. R. Silva" gustavoars@kernel.org Cc: stable@vger.kernel.org
Build problem aside, why is this a stable kernel issue?
My thinking was that since this is technically a UAPI change, it'd be best to get it changed as widely as possible.
You can't break the uapi, so it should be the same with or without your change right?
confused,
greg k-h