From: Kees Cook <keescook@xxxxxxxxxxxx>
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-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>
Link: https://lore.kernel.org/r/20230105190507.gonna.131-kees@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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);
};
};
