From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 29B63267B99; Mon, 24 Feb 2025 11:19:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740395951; cv=none; b=MHdiBdg60qWvIsott0/GF7SXOtpnDoyWEHURPIaIvXqhPLM5oA5odBDAmW7Ti1TJ3jATDxtXVI5xoD8uRE48An+96PWuqCRX5yiv4totxQGa++RaNy+oeO/1LZCD1OZCvnztWkhJMkmmCXPzGTL/YI4NjsNfrOTyRYiwp8pVo04= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740395951; c=relaxed/simple; bh=gNhpMd6xhiiiI7IQjUh5qom9njguHMcExPCIvyTQ+oE=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=MRYOaELA70zvFwDqpNMGHYOI908JbuO2W4+XrUJq3E/8tzi/q8NuMjWgvH6yhYv7sVzurjl8Spcogu2dDbQIPsblBuTCk0LHh4x4aYe1i4lzSOiSFVavbLLmK0Lhi3yieZ+oWNSVfwODqwphvHPaYlNa1ZF/N1ZYdAqmUiUIg4c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=CjS81hmm; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="CjS81hmm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 63CBBC4CEE6; Mon, 24 Feb 2025 11:19:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1740395950; bh=gNhpMd6xhiiiI7IQjUh5qom9njguHMcExPCIvyTQ+oE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CjS81hmmhGBxah9AF3h+osKhV0f7bQpHN74v07x3fhisLG3Z/ZT1yc/hAHN1+pkI7 2ZbpNxD9a0T65+P01yXw29EPx0BxcDBnKXo+oTkqZGqsCVp7z6OZt7i/wyBa1uLFNn 8TjKu5Evmh8FG41wImeX+uxyNUuQ/mXGVnNi6E0FGLH9KNNTZZJkiHSEkEMcOTVhDC 04hMs0FYFgZQnoY/Zlj+qKuSny8rvH89vRsOp4El5eDFmwDDduWmIRccvX2SF7TSMy tY3nHt0chbKtXpZW/1cQcnheMwxwiUTAH6pHg6U4HHVfpFjkD2O6QxrxFxOE+D8Y4i UhzgDjdAPeJUg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Yu-Chun Lin , Jakub Kicinski , Sasha Levin , marcelo.leitner@gmail.com, lucien.xin@gmail.com, davem@davemloft.net, edumazet@google.com, pabeni@redhat.com, linux-sctp@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 6.12 26/28] sctp: Fix undefined behavior in left shift operation Date: Mon, 24 Feb 2025 06:17:57 -0500 Message-Id: <20250224111759.2213772-26-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250224111759.2213772-1-sashal@kernel.org> References: <20250224111759.2213772-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-sctp@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.12.16 Content-Transfer-Encoding: 8bit From: Yu-Chun Lin [ Upstream commit 606572eb22c1786a3957d24307f5760bb058ca19 ] According to the C11 standard (ISO/IEC 9899:2011, 6.5.7): "If E1 has a signed type and E1 x 2^E2 is not representable in the result type, the behavior is undefined." Shifting 1 << 31 causes signed integer overflow, which leads to undefined behavior. Fix this by explicitly using '1U << 31' to ensure the shift operates on an unsigned type, avoiding undefined behavior. Signed-off-by: Yu-Chun Lin Link: https://patch.msgid.link/20250218081217.3468369-1-eleanor15x@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/sctp/stream.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/sctp/stream.c b/net/sctp/stream.c index c241cc552e8d5..bfcff6d6a4386 100644 --- a/net/sctp/stream.c +++ b/net/sctp/stream.c @@ -735,7 +735,7 @@ struct sctp_chunk *sctp_process_strreset_tsnreq( * value SHOULD be the smallest TSN not acknowledged by the * receiver of the request plus 2^31. */ - init_tsn = sctp_tsnmap_get_ctsn(&asoc->peer.tsn_map) + (1 << 31); + init_tsn = sctp_tsnmap_get_ctsn(&asoc->peer.tsn_map) + (1U << 31); sctp_tsnmap_init(&asoc->peer.tsn_map, SCTP_TSN_MAP_INITIAL, init_tsn, GFP_ATOMIC); -- 2.39.5