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 A0D4A39794E for ; Tue, 8 Sep 2026 23:21:11 +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=1788909672; cv=none; b=gUBRulsxvqKz3+7g5RfwTSSled2ljCYnXF/LmKIF1LsTBpODvq9Vj8KbCv0b2DB04RjKoZybyOvbY8VbbeTTrvuDXQONnTXkDo7scX+F65wK5gci2u6v9EussEBOcLVFw9Vi9IGO/4qXq1iH6T2cNcmC6c9NA6k2xVl8UtMEmhc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788909672; c=relaxed/simple; bh=RMBLlQsSuPNQ2TJ1bbptzWouIQo7GGBAdq9Nm6z1sa4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=VKKMNEdFO0y5vHwq64D3AZDweMDCNk31XPjvyfDco8dt7SHCqHhinpipqUDxoA4Q4xRFDlmcyC/xpqitiAlXKodlcuX6w40LYP/nzhZOvCtKjuyykp34sHcREMRamiwndYGQMnCBTfYl9WOSlHDuYfYAMWS9qFa04jzYwZfIhIs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=TPBw6D/S; 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="TPBw6D/S" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E1DFD1F00A3A; Tue, 8 Sep 2026 23:21:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788909671; bh=fnluLFQRgZTePeEzd6yh5Zg499/EVmQBRdGWkPtdWgE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=TPBw6D/Scsv12kegF9bWLlidwqs7ByQT+7mGDdaTik1WVo0FFiSJyJKuvuCyIO+8T j6BJ6m28pY6Gm2WkfzRCKLPJdRFFhgFEUMdlGMbF1NfRCoQscs6/F55OT6I1cEumen RysBcpNJxEurgwTEo4TRDrwSY4AVB1c6sBkFT7XOkYuhAwdVgloVgbRe/RiZj8H2n8 a2pr5sfA97s0vOuqeHx2WTZLV3DLG8dDHZHqp/lsoAkXbKOkkNVu+NnTVZ5t/vaWtJ ZTfoYCB+W1XMgRws2sX02WsgT+NG2OBcKpkID+sFokN2WEiJbPbQ1w/9G+b5zCSNLx Pf0QgsBUCan1Q== From: Sasha Levin To: stable@vger.kernel.org Cc: Chuck Lever , Sasha Levin Subject: [PATCH 6.18.y] rpcrdma: arm rn_done before publishing the notification Date: Tue, 8 Sep 2026 19:21:09 -0400 Message-ID: <20260908232109.629807-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026090359-lingo-expletive-e654@gregkh> References: <2026090359-lingo-expletive-e654@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