io_uring/zctx: check chained notif contexts

Send zc only links ubuf_info for requests coming from the same context.
There are some ambiguous syz reports, so let's check the assumption on
notification completion.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/fd527d8638203fe0f1c5ff06ff2e1d8fd68f831b.1755179962.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/io_uring/notif.c b/io_uring/notif.c
index 9a6f6e92d742428bb9d7c30c8b788f19ddab1501..8c92e9cde2c61c275a8ed99108154619d5e0bf0b 100644 (file)
--- a/io_uring/notif.c
+++ b/io_uring/notif.c
@@ -14,10 +14,15 @@ static const struct ubuf_info_ops io_ubuf_ops;
 static void io_notif_tw_complete(struct io_kiocb *notif, io_tw_token_t tw)
 {
        struct io_notif_data *nd = io_notif_to_data(notif);
+       struct io_ring_ctx *ctx = notif->ctx;
+
+       lockdep_assert_held(&ctx->uring_lock);
 
        do {
                notif = cmd_to_io_kiocb(nd);
 
+               if (WARN_ON_ONCE(ctx != notif->ctx))
+                       return;
                lockdep_assert(refcount_read(&nd->uarg.refcnt) == 0);
 
                if (unlikely(nd->zc_report) && (nd->zc_copied || !nd->zc_used))