On Thu, Jan 05, 2023 at 11:05:11AM -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 > Cc: io-uring@xxxxxxxxxxxxxxx > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> Reviewed-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx> Thanks! -- Gustavo > --- > v2: use helper since these flex arrays are in a union. > v1: https://lore.kernel.org/lkml/20230105033743.never.628-kees@xxxxxxxxxx > --- > include/uapi/linux/io_uring.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h > index 2780bce62faf..434f62e0fb72 100644 > --- a/include/uapi/linux/io_uring.h > +++ b/include/uapi/linux/io_uring.h > @@ -625,7 +625,7 @@ struct io_uring_buf_ring { > __u16 resv3; > __u16 tail; > }; > - struct io_uring_buf bufs[0]; > + __DECLARE_FLEX_ARRAY(struct io_uring_buf, bufs); > }; > }; > > -- > 2.34.1 >
