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 5451F2F8E8B; Fri, 7 Aug 2026 15:08:20 +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=1786115301; cv=none; b=XpNgagHXFruwN/blQdHlIY61ncdWGSB1DCYJtvMtcSBtvv4l1DWn7QHX7rgbp3rlSvAOPPlmeVOGtRgj6UIUv30FB1yGCq+9fMClBH/ayO0nk5O51SAvUczLEmZPexz8d+dFY7nsjEDfauGZtg+oyVmWzcLK8/IywlVFd51kbbQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786115301; c=relaxed/simple; bh=dVsjYZNntEZglwMFxOzEiBGDqcb6CuRzBEKcIQnJCcQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=mFv1WYe6Jy2NO1ALkWFf7wHCe/JWeRYWZ6pLIOx+cPKiXX0grX+qDovRSFUU/Yy+cX1oXFboLpBK+32iaChg/zmqMdcjr/qZj6SMVoeTrgVmrYIWZ6T27YWRaPLA/g4mjz6LGQjN3QF7h02Cy8lCpkRkBEZie5BEKyxAQVIixFg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=lviOnDqP; 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="lviOnDqP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AF32B1F000E9; Fri, 7 Aug 2026 15:08:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786115300; bh=O+3ouD3GtP/enX7ojqhAs8DHWZQx/g8tK7JgmrKiWgA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=lviOnDqPpMlBdGNBqV752IoLS6UIEQrc29FPIJKcQKHEBg3ZNYZbkEo4gpXg95fkA h80R9mYLxkhM+ThyFyvH0UWEmqpF44GpoterE6bh7XpRarCtHnIYcjU6ySRcWE3Zx2 9cA343KdfVsQ46/W7a5ysuISCL+wHlvfmN6B1OrY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Xuanqiang Luo , Mahanta Jambigi , Paolo Abeni Subject: [PATCH 6.18 226/396] net/smc: fix socket use-after-free during link group termination Date: Fri, 7 Aug 2026 16:36:26 +0200 Message-ID: <20260807143429.137014456@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260807143424.272339768@linuxfoundation.org> References: <20260807143424.272339768@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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xuanqiang Luo commit f621d6ebeebb6374342571e4ddf45fdbc420f6cd upstream. __smc_lgr_terminate() drops conns_lock after finding a connection in lgr->conns_all, but before taking a reference on its socket. The connection is embedded in the socket, and its registration reference protects it only while the connection remains in the tree. A concurrent close can unregister the connection and drop that reference, freeing the socket before the termination worker reaches sock_hold(). The race is reachable when close overlaps link group termination. Local stress testing reproduced the use-after-free and KASAN reported: BUG: KASAN: slab-use-after-free in __smc_lgr_terminate.part.0 [smc] Write of size 4 by task kworker/3:3 Workqueue: events smc_lgr_terminate_work [smc] __smc_lgr_terminate.part.0 [smc] The socket was allocated by smc_create(), freed through slab_free_after_rcu_debug(), and was followed by: refcount_t: addition on 0; use-after-free. __smc_lgr_terminate.part.0 [smc] Take the socket reference while conns_lock still protects the tree entry. The unregister path then cannot drop the last reference until termination has finished using the socket. Fixes: 69318b5215f2 ("net/smc: improve abnormal termination locking") Cc: stable@vger.kernel.org Signed-off-by: Xuanqiang Luo Reviewed-by: Mahanta Jambigi Link: https://patch.msgid.link/20260723105454.87016-1-xuanqiang.luo@linux.dev Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman --- net/smc/smc_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/smc/smc_core.c +++ b/net/smc/smc_core.c @@ -1558,10 +1558,10 @@ static void __smc_lgr_terminate(struct s read_lock_bh(&lgr->conns_lock); node = rb_first(&lgr->conns_all); while (node) { - read_unlock_bh(&lgr->conns_lock); conn = rb_entry(node, struct smc_connection, alert_node); smc = container_of(conn, struct smc_sock, conn); sock_hold(&smc->sk); /* sock_put below */ + read_unlock_bh(&lgr->conns_lock); lock_sock(&smc->sk); smc_conn_kill(conn, soft); release_sock(&smc->sk);