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.