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 20ADC4E56F1 for ; Thu, 3 Sep 2026 15:38:42 +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=1788449923; cv=none; b=fKGxzDKoAr1YWD854xuHvEtXgVom8YhWjyMkk93Ny5QDLrVzHx9xghwPdAYBBPc8Yl2dRpDLadsbSfZX8geXQFsdwJgqytWllKHf1yWg9OiVdyU3SH/YcSxmyNP0L3UrcOpfyWlpoHZfXobqYpAdEB7wyzA6Jfv7ACs/sreTmQU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788449923; c=relaxed/simple; bh=sIeGSBWfyVWiiGYPZaGXsbBafZqKWS8/h8tcUfsxM08=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=DZWCOl7butIZhCj1ex/r9lquS1ymN6mS9WywHH2NkMGPk0Io1Qu1/9AHcNQkhyydvIjksPjoZPmSWUzZZojde01O2Fv+7rWpOlrKJu4erYMlGxeCWe9GzjQZG6tE/6IbACuOxE+L+wKfoBt+vJH0MXLFRhPTRfNR4KXPkQ5JQbc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=LnZ3WBUT; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="LnZ3WBUT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5E2431F00A3A; Thu, 3 Sep 2026 15:38:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788449921; bh=ROaqAiXndar9UyKq3GViLdYveFe5yG6WeCpokyy7Yco=; h=Subject:To:Cc:From:Date; b=LnZ3WBUTlp3dso5cEQDtwv/C2C+vqxEEiKdw51vtd244m23DpqUI3NYREejf0ItJS jaD0FnKehJyxjyCYkoTHZU+rkBbmWEFMubnz/HyVmUFiikNKo7w7qU79J6OaaCxudV qYKuHZsvJ4rcjRMIBRM9wig1m4YAZ7n77px7MFbI= Subject: FAILED: patch "[PATCH] net/smc: fix socket refcount leak in smc_switch_conns()" failed to apply to 5.10-stable tree To: hidayath@linux.ibm.com,kuba@kernel.org,leitao@debian.org,mjambigi@linux.ibm.com Cc: From: Date: Thu, 03 Sep 2026 17:09:44 +0200 Message-ID: <2026090344-afraid-primarily-b3a0@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x 719296c4aa8213d4ac8002e77d5956d436bc98d0 # git commit -s git send-email --to '' --in-reply-to '2026090344-afraid-primarily-b3a0@gregkh' --subject-prefix 'PATCH 5.10.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 719296c4aa8213d4ac8002e77d5956d436bc98d0 Mon Sep 17 00:00:00 2001 From: Hidayath Khan Date: Thu, 20 Aug 2026 16:47:29 +0200 Subject: [PATCH] net/smc: fix socket refcount leak in smc_switch_conns() smc_switch_conns() takes a reference on the SMC socket before dropping lgr->conns_lock, so the connection stays alive while the CDC slot is fetched: sock_hold(&smc->sk); read_unlock_bh(&lgr->conns_lock); /* pre-fetch buffer outside of send_lock, might sleep */ rc = smc_cdc_get_free_slot(conn, to_lnk, &wr_buf, NULL, &pend); if (rc) goto err_out; The err_out label only drops the wr_tx link reference, so this early exit returns without the matching sock_put(). The second error exit is not affected, because sock_put() has already run by then. A leaked sk_refcnt means the smc_sock is never destroyed. Its send and receive buffers stay allocated, and for a user socket the reference held on the network namespace is never released, so the netns can no longer be torn down. smc_cdc_get_free_slot() fails when the target link goes down or when the connection has been killed while the switch is in progress. Both are reachable during the link failover this function implements, so the leak is triggered by the same hardware events that make smc_switch_conns() run in the first place. Restructure so there is a single sock_put() covering both outcomes, instead of adding a second one to the error path. Fixes: 95f7f3e7dc6b ("net/smc: improved fix wait on already cleared link") Cc: stable@vger.kernel.org Reviewed-by: Mahanta Jambigi Reviewed-by: Breno Leitao Signed-off-by: Hidayath Khan Link: https://patch.msgid.link/20260820144729.1019399-1-hidayath@linux.ibm.com Signed-off-by: Jakub Kicinski diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c index 181647982490..04aedd957543 100644 --- a/net/smc/smc_core.c +++ b/net/smc/smc_core.c @@ -1148,13 +1148,13 @@ struct smc_link *smc_switch_conns(struct smc_link_group *lgr, read_unlock_bh(&lgr->conns_lock); /* pre-fetch buffer outside of send_lock, might sleep */ rc = smc_cdc_get_free_slot(conn, to_lnk, &wr_buf, NULL, &pend); - if (rc) - goto err_out; - /* avoid race with smcr_tx_sndbuf_nonempty() */ - spin_lock_bh(&conn->send_lock); - smc_switch_link_and_count(conn, to_lnk); - rc = smc_switch_cursor(smc, pend, wr_buf); - spin_unlock_bh(&conn->send_lock); + if (!rc) { + /* avoid race with smcr_tx_sndbuf_nonempty() */ + spin_lock_bh(&conn->send_lock); + smc_switch_link_and_count(conn, to_lnk); + rc = smc_switch_cursor(smc, pend, wr_buf); + spin_unlock_bh(&conn->send_lock); + } sock_put(&smc->sk); if (rc) goto err_out;