From 991fe08f3e9771111e2349123fa29871ad11ca55 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 12 Mar 2026 22:59:25 +0800 Subject: [PATCH] io_uring/kbuf: check if target buffer list is still legacy on recycle ANBZ: #34999 commit 439a6728ec4641ffad1ca796622c19bc525e570f stable. Commit c2c185be5c85d37215397c8e8781abf0a69bec1f upstream. There's a gap between when the buffer was grabbed and when it potentially gets recycled, where if the list is empty, someone could've upgraded it to a ring provided type. This can happen if the request is forced via io-wq. The legacy recycling is missing checking if the buffer_list still exists, and if it's of the correct type. Add those checks. Cc: stable@vger.kernel.org Fixes: c7fb19428d67 ("io_uring: add support for ring mapped supplied buffers") Reported-by: Keenan Dong Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman Fixes: CVE-2026-43366 Assisted-by: PatchPilot Signed-off-by: Ferry Meng --- io_uring/kbuf.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/io_uring/kbuf.c b/io_uring/kbuf.c index b2c381634393..ad1e14359662 100644 --- a/io_uring/kbuf.c +++ b/io_uring/kbuf.c @@ -70,9 +70,15 @@ void io_kbuf_recycle_legacy(struct io_kiocb *req, unsigned issue_flags) buf = req->kbuf; bl = io_buffer_get_list(ctx, buf->bgid); - list_add(&buf->list, &bl->buf_list); + /* + * If the buffer list was upgraded to a ring-based one, or removed, + * while the request was in-flight in io-wq, drop it. + */ + if (bl && !bl->is_mapped) + list_add(&buf->list, &bl->buf_list); req->flags &= ~REQ_F_BUFFER_SELECTED; req->buf_index = buf->bgid; + req->kbuf = NULL; io_ring_submit_unlock(ctx, issue_flags); return; -- Gitee