From 97b57f69fee1b61b41acbf37e7720cac9d389fa4 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 12 Mar 2026 08:59:25 -0600 Subject: io_uring/kbuf: check if target buffer list is still legacy on recycle 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 --- io_uring/kbuf.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/io_uring/kbuf.c b/io_uring/kbuf.c index dae5b4ab3819..e7f444953dfb 100644 --- a/io_uring/kbuf.c +++ b/io_uring/kbuf.c @@ -111,9 +111,18 @@ bool 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); - bl->nbufs++; + /* + * 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->flags & IOBL_BUF_RING)) { + list_add(&buf->list, &bl->buf_list); + bl->nbufs++; + } else { + kfree(buf); + } req->flags &= ~REQ_F_BUFFER_SELECTED; + req->kbuf = NULL; io_ring_submit_unlock(ctx, issue_flags); return true; -- cgit v1.2.3