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io_uring/kbuf: check if target buffer list is still legacy on recycle

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Commit c2c185be5c 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: c7fb19428d ("io_uring: add support for ring mapped supplied buffers")
Reported-by: Keenan Dong <keenanat2000@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jens Axboe
2026-03-12 08:59:25 -06:00
committed by Greg Kroah-Hartman
parent d77401968c
commit 439a6728ec
1 changed files with 7 additions and 1 deletions
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io_uring/kbuf.c
+7 -1
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@@ -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;