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-and-one-element-arrays > > > > Fixes: c7fb19428d67 ("io_uring: add support for ring mapped supplied buffers") > > Cc: Jens Axboe <axboe@xxxxxxxxx> > > Cc: Pavel Begunkov <asml.silence@xxxxxxxxx> > > Cc: "Gustavo A. R. Silva" <gustavoars@xxxxxxxxxx> > > Cc: stable@xxxxxxxxxxxxxxx > > 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. -- Kees Cook
