From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 891902EEE7E for ; Tue, 8 Sep 2026 23:25:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788909910; cv=none; b=M7rwkXzQA8Co8wgyTaxqhUPMs7NDG2fTXMmGGpxk39NL/wWJNxHbbCY3DWk0eEShM/vCb4Lbmf8KJHYR9sVsuLSzsdEijsLzg+RUESkV8gl4606ffz9GY7ULvVzsH2wi0w0yJ2QrdHFGKHJgSbwy+L/P3UgnpjwTIGYHyRjg/dM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788909910; c=relaxed/simple; bh=RMBLlQsSuPNQ2TJ1bbptzWouIQo7GGBAdq9Nm6z1sa4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=uPYDtthz/plIUhMFn6gQk1Ykz0n349AHt2h1hV/RjRtcxUzjefW8FIDvWgySnnjW91QoLlqThG7V/EgKt0Pl9lBEY3MUTc41FfcX30Cz8nR4d7ni3GJ0ZJgTy2f4OA9MlGXmDJKEEEPHQl00FnaGvkvAVlIeNWwRvA/dGP/sNXk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dejJyf9m; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="dejJyf9m" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E5D991F00A3A; Tue, 8 Sep 2026 23:25:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788909909; bh=fnluLFQRgZTePeEzd6yh5Zg499/EVmQBRdGWkPtdWgE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=dejJyf9mRCZoApyKqFab1+UOKEoLII7cPuULhderLSR26GFIG4hiYaeQIi6RWcolD S9tmNrs6ISQLGFC5LTFnTPkzOr1kSVBlaeluppya7I3p+3spQEuZa0t75YqKCIXy// wJL75puwd89Mr6YdSdoXb/Ep5/aMkdeGrPTk3fc9RCUrGWUHwibdNmpiJA/0d5/NrA b1XpqMBLLSf3m3jQ5nFbxfGbeqn4IhP5NGKj3PfHI28mXQfzm58MauQkga06Se/gz0 bIaE/RkLY/G5yRQoDEQtcE7pp0gkpQj84yOwyw0N09GmGDyyL8HW61yOw12DVBNn5R RvaFVpzUeJhZg== From: Sasha Levin To: stable@vger.kernel.org Cc: Chuck Lever , Sasha Levin Subject: [PATCH 6.12.y] rpcrdma: arm rn_done before publishing the notification Date: Tue, 8 Sep 2026 19:25:06 -0400 Message-ID: <20260908232506.644986-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026090359-consensus-citizen-be20@gregkh> References: <2026090359-consensus-citizen-be20@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Chuck Lever [ Upstream commit 5b06f706374c37375bdff9d21cc10e61df925a92 ] rpcrdma_rn_register() inserts @rn into rd_xa with xa_alloc() before storing the caller's callback in rn->rn_done. The xarray makes @rn reachable to rpcrdma_remove_one(), which walks rd_xa and invokes rn->rn_done(rn) for every registered notification. A device removal that races a fresh registration can therefore observe @rn with rn_done still NULL, because the notification objects are zero allocated by their owners, and call through a NULL function pointer. Store rn->rn_done before xa_alloc() publishes @rn. The xarray's store-side and load-side ordering then guarantees that any CPU which finds @rn in rd_xa also observes the armed callback. rpcrdma_rn_unregister() treats a non-NULL rn_done as the sentinel for a completed registration, so the early store must not survive a failed registration. Clear rn_done again when xa_alloc() fails. Were it left set, the failed-accept cleanup path would call rpcrdma_rn_unregister() on an @rn that was never inserted, erasing an unrelated rd_xa slot and underflowing rd_kref. Fixes: 7e86845a0346 ("rpcrdma: Implement generic device removal") Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260601201703.46078-1-cel@kernel.org Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin --- net/sunrpc/xprtrdma/ib_client.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) diff --git a/net/sunrpc/xprtrdma/ib_client.c b/net/sunrpc/xprtrdma/ib_client.c index cfc24e21d260c..888638318b6dd 100644 --- a/net/sunrpc/xprtrdma/ib_client.c +++ b/net/sunrpc/xprtrdma/ib_client.c @@ -52,8 +52,8 @@ static struct rpcrdma_device *rpcrdma_get_client_data(struct ib_device *device) * is unregistered first. * * On failure, a negative errno is returned. rn->rn_done is left - * NULL on every failure path (it is assigned only after xa_alloc - * and kref_get have both succeeded), so the @rn may safely be + * NULL on every failure path (it is armed before xa_alloc but + * cleared again if xa_alloc fails), so the @rn may safely be * passed to rpcrdma_rn_unregister() without a separate * registered/unregistered flag in the caller. */ @@ -66,10 +66,21 @@ int rpcrdma_rn_register(struct ib_device *device, if (!rd || test_bit(RPCRDMA_RD_F_REMOVING, &rd->rd_flags)) return -ENETUNREACH; - if (xa_alloc(&rd->rd_xa, &rn->rn_index, rn, xa_limit_32b, GFP_KERNEL) < 0) + /* + * Arm rn_done before xa_alloc() publishes @rn: once @rn is + * visible in rd_xa, a concurrent rpcrdma_remove_one() can + * call rn->rn_done(), so the pointer must already be set. + * + * Restore NULL if xa_alloc() fails. rn_done doubles as the + * registration sentinel for rpcrdma_rn_unregister(); a stale + * value would unregister an @rn that was never inserted. + */ + rn->rn_done = done; + if (xa_alloc(&rd->rd_xa, &rn->rn_index, rn, xa_limit_32b, GFP_KERNEL) < 0) { + rn->rn_done = NULL; return -ENOMEM; + } kref_get(&rd->rd_kref); - rn->rn_done = done; trace_rpcrdma_client_register(device, rn); return 0; } @@ -102,8 +113,9 @@ void rpcrdma_rn_unregister(struct ib_device *device, /* * rn_done is the registration sentinel: rpcrdma_rn_register - * assigns it last, after xa_alloc and kref_get have both - * succeeded. A NULL rn_done means this notification was + * leaves it NULL on every failure path, clearing it again if + * xa_alloc fails, so a non-NULL rn_done marks a completed + * registration. A NULL rn_done means this notification was * never registered (or its registration failed) or has * already been unregistered, and the call is a no-op. * Without this guard, rn_index == 0 from a kzalloc'd -- 2.53.0