From 3851d25c75ed03117268a8feb34adca5a843a126 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 10 Nov 2022 10:50:55 -0700 Subject: [PATCH] io_uring: check for rollover of buffer ID when providing buffers We already check if the chosen starting offset for the buffer IDs fit within an unsigned short, as 65535 is the maximum value for a provided buffer. But if the caller asks to add N buffers at offset M, and M + N would exceed the size of the unsigned short, we simply add buffers with wrapping around the ID. This is not necessarily a bug and could in fact be a valid use case, but it seems confusing and inconsistent with the initial check for starting offset. Let's check for wrap consistently, and error the addition if we do need to wrap. Reported-by: Olivier Langlois Link: https://github.com/axboe/liburing/issues/726 Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe --- io_uring/kbuf.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/io_uring/kbuf.c b/io_uring/kbuf.c index 25cd724ade18..e2c46889d5fa 100644 --- a/io_uring/kbuf.c +++ b/io_uring/kbuf.c @@ -346,6 +346,8 @@ int io_provide_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe tmp = READ_ONCE(sqe->off); if (tmp > USHRT_MAX) return -E2BIG; + if (tmp + p->nbufs >= USHRT_MAX) + return -EINVAL; p->bid = tmp; return 0; }