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 642652561A0; Mon, 24 Feb 2025 11:21:21 +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=1740396081; cv=none; b=G98X40bDcecvQdB/Ae4fd9dCUT47jvanfcZIbM+S7bvGk2bhTG5DYUDYksI7td4gN8i+0cjZSspMqzx3wnc1ndBVda4m7aIaTeATGTwlm6vpnPju/4MSIucdgdc+OQRfVPvu2IN9Yp9VQMOfWLyXZ6b/NDWBVKJ8YQkWx8wTGRI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740396081; c=relaxed/simple; bh=9afY757v31G/u4/cA1tFUd2NgpHJZ6SIDg0Ev4eo5EQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=kYot2dLFLuz6LdSeORwIVP73Bn49Xqphul0y+QUEI2EwUb62rYZS5SH8F8ECSuywZP0i0RAunS8rMLBWRMpRWYOVoFUEoHlMqf6BcmFP3g1xMRp0AO/zVoKukIyw7fFjRpCj7sL8aVOEs8/Q+BlibsZHHIkNkwQAoLrLDqJhqfs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nAqOArFn; 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="nAqOArFn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F2ABEC4CED6; Mon, 24 Feb 2025 11:21:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1740396081; bh=9afY757v31G/u4/cA1tFUd2NgpHJZ6SIDg0Ev4eo5EQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nAqOArFnhPs7fBhURpVhNYmkDucOlL/QC/P6V69Hvx+oQ+lIcWuUbtkhMUfEtQJME JAUYTmYQKrvb5v8yyKWEKceycTAHXdRAEocvwY/CMkh0zKAK3NAOIiMKKGKxYSkeJK sGPFNAMrsIhsP2apG3CRfahvjhE2H1rLTIfZYDrXHAVf9S2MSAaOm1zCktVksJ05J7 yAbGYDnL8NiDpokq3EM0pUnwQLOfecm0ke9aGf58u3g8/qNSZdpJz1v3A9cJmj7ID/ v99kONDO1hr0AfrMXqL6vDFc2cc5MmT/jREpXWTbGRHwYNpuV68LEO3Y9i/umXjaTW AoeupRe75VHkA== 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 5.4 3/4] sctp: Fix undefined behavior in left shift operation Date: Mon, 24 Feb 2025 06:21:11 -0500 Message-Id: <20250224112115.2215137-3-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250224112115.2215137-1-sashal@kernel.org> References: <20250224112115.2215137-1-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 5.4.290 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 ca8fdc9abca5f..08cd06078fab1 100644 --- a/net/sctp/stream.c +++ b/net/sctp/stream.c @@ -736,7 +736,7 @@ 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