From: Kees Cook keescook@chromium.org
commit 36632d062975a9ff4410c90dd6d37922b68d0920 upstream.
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 Cc: io-uring@vger.kernel.org Signed-off-by: Kees Cook keescook@chromium.org Reviewed-by: Gustavo A. R. Silva gustavoars@kernel.org Link: https://lore.kernel.org/r/20230105190507.gonna.131-kees@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/uapi/linux/io_uring.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/include/uapi/linux/io_uring.h +++ b/include/uapi/linux/io_uring.h @@ -617,7 +617,7 @@ struct io_uring_buf_ring { __u16 resv3; __u16 tail; }; - struct io_uring_buf bufs[0]; + __DECLARE_FLEX_ARRAY(struct io_uring_buf, bufs); }; };