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 8A24C3BBFA1; Mon, 17 Aug 2026 13:42:26 +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=1786974147; cv=none; b=oXK+0tk+Ysf5fLEfh7gLcVfCTdlOO2jLXwg/sg+agyFnmTigOfHX3aOCpmS7CIHTu6m7WV3kYAc/hZFUkCb+S033ZMdrBKNqPtnHy91UVatDATEIWjlhExXcZAmNUI/wE0czC5R+BCRe3yfK2Upop6+lulQbseolQvSmFmNyvLE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786974147; c=relaxed/simple; bh=zeV7MFW/JS//ESaG1yWOb1lWpfc3HT7YRXMUzyOX2Ug=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=JBFCDx3mck5lcY1YeoMDOA2Pua13/rk0CJ+s8T1HpHJRLDVwg8k5+Np3fImoQPYSbtwxWqvtaDhb0tpkEJftYnC553G8NUxq+4Lqlyz9QcDIc/M+omRtrPttRk/fnOfESVQESgkaINF1k+a+Ghrhcyaj9te59tL2Hy0//bFXrVs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=rwb7o77Z; 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="rwb7o77Z" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EA5A61F000E9; Mon, 17 Aug 2026 13:42:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786974146; bh=3gGpEW9HX0Sn3SSbXHfpFM8HmlVFH57i2it4LDlTK+I=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=rwb7o77ZJLOA7V4oSeBEKWO3T+mf3AC7c8aYWJAeRH8rudfdCKAOzovjDUg2xkhqn cpaAQVSQiNCXLNFDOew7q3LhtRLkCYe3Cx0Y4jde+NcUPb/pSR6X2/iDlNB+u+B8Tl HVvHRw19hWOdhR4WL9kRdnP0rFkX2q75VeGVK9VI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Mahanta Jambigi , Sidraya Jayagond , Breno Leitao , Dust Li , Paolo Abeni , Sasha Levin Subject: [PATCH 7.1 105/271] net/smc: fix TOCTOU race between smc_listen_out() and listener close Date: Mon, 17 Aug 2026 15:30:30 +0200 Message-ID: <20260817132541.157053531@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260817132536.752504388@linuxfoundation.org> References: <20260817132536.752504388@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 7.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sidraya Jayagond [ Upstream commit 185a4caeecabc150106deda1da170b09f2ad803f ] smc_listen_out() reads lsmc->sk.sk_state without the listener lock, then acquires lock_sock_nested() only after the check passes. This opens a window where smc_close_active() can transition the listener to SMC_CLOSED, call smc_close_cleanup_listen() to drain the accept queue, and release the lock, all between the lockless read and the delayed lock acquisition: smc_listen_work (smc_hs_wq) smc_close_active() ------------------------------- ------------------------- release_sock(child) if (sk_state == SMC_LISTEN) TRUE lock_sock(listener) sk_state = SMC_CLOSED smc_close_cleanup_listen() release_sock(listener) flush_work(tcp_listen_work) lock_sock_nested(listener) smc_accept_enqueue(listener, child) /* child enqueued on dead listener */ smc_close_active() flushes only tcp_listen_work. Work items already dispatched onto smc_hs_wq for the CLC handshake continue running unguarded. smc_accept_enqueue() takes a sock_hold() on the child that is never released, so the child smc_sock, its clcsock, and the reference all leak. A remote peer that opens TCP connections while the server calls close() can exhaust kernel memory. Move lock_sock_nested() to before the sk_state check so that the test and the enqueue are atomic under the listener lock. Fixes: fd57770dd198 ("net/smc: wait for pending work before clcsock release_sock") Reviewed-by: Mahanta Jambigi Signed-off-by: Sidraya Jayagond Reviewed-by: Breno Leitao Reviewed-by: Dust Li Link: https://patch.msgid.link/20260803070701.126339-1-sidraya@linux.ibm.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- net/smc/af_smc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c index b5db69073e20f..00403175b7406 100644 --- a/net/smc/af_smc.c +++ b/net/smc/af_smc.c @@ -1931,11 +1931,12 @@ static void smc_listen_out(struct smc_sock *new_smc) atomic_dec(&lsmc->queued_smc_hs); release_sock(newsmcsk); /* lock in smc_listen_work() */ + lock_sock_nested(&lsmc->sk, SINGLE_DEPTH_NESTING); if (lsmc->sk.sk_state == SMC_LISTEN) { - lock_sock_nested(&lsmc->sk, SINGLE_DEPTH_NESTING); smc_accept_enqueue(&lsmc->sk, newsmcsk); release_sock(&lsmc->sk); } else { /* no longer listening */ + release_sock(&lsmc->sk); smc_close_non_accepted(newsmcsk); } -- 2.53.0