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 57154417BF8; Fri, 4 Sep 2026 06:20:56 +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=1788502857; cv=none; b=R2tqDLDCV8oTPVmMJXya+4ehhU3oOBuNXJUFNg6pQOfg2mfnXAJrH6mZ688HMAtYJ8J0hiuLkRuFP1JALuZRnN7eAO6/R+SeJm7Jtm4az9HmF+CkU+ovvyOmysM7QYO8MBWgE4OBN3gUs607CppewsQPYu+uDQGmXJnLtN/R+lw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788502857; c=relaxed/simple; bh=5tj0bUPpSr6tknFtU55tg2rnxt1b9yE17BXyVTSi/Zk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=c6lwCP6hhOioVXzHuK98DJlURIAZEuXMC0IyD2Wwgv5qPL74SUPoJVDdImpkPnNEjXlYMYD3GvQ/NUrfQB5PNWVBzRN3U9LBxW2ilsdbwmrKH+kGMasnKXV80E1pGmKI8n7ruNoFYJ3+Sj8I31N/6kTW2DCAUc1uzK400cZvzng= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=nxMyNH0G; 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="nxMyNH0G" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AE53F1F00A3E; Fri, 4 Sep 2026 06:20:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788502856; bh=PXJEAatYkR8DylZP8difJ11sJxihwCncKEZkXDovBkg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=nxMyNH0GNHeLeMVNFZN5KJn6f5mBzf9CROm9OKiw236U7xGMV3/dgWxz5EHIn2vml g6rTqM1Ag9lh3si2XQNH/ItbNFDx9pfGOAnPd7LlsiE7Kx0uPupvpeLwYtH1TIjEu5 N1XG3tot4HkXYU3fhLOrv63Hw+nytQf32Zd94yHk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Mahanta Jambigi , Breno Leitao , Hidayath Khan , Jakub Kicinski Subject: [PATCH 6.12 353/403] net/smc: fix socket refcount leak in smc_switch_conns() Date: Fri, 4 Sep 2026 07:02:36 +0200 Message-ID: <20260904045742.841551458@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260904045734.806166532@linuxfoundation.org> References: <20260904045734.806166532@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Hidayath Khan commit 719296c4aa8213d4ac8002e77d5956d436bc98d0 upstream. 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 Signed-off-by: Greg Kroah-Hartman --- net/smc/smc_core.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) --- a/net/smc/smc_core.c +++ b/net/smc/smc_core.c @@ -1129,13 +1129,13 @@ again: 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;