From nobody Sun Feb 8 09:32:55 2026 Received: from codeconstruct.com.au (pi.codeconstruct.com.au [203.29.241.158]) (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 25F813815C2; Tue, 13 Jan 2026 09:01:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=203.29.241.158 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768294931; cv=none; b=a0sN1Rg77h5iy6hAL3b2Oqc4n28GP//laKo7WqNPFqc8epYGMrpQp5t45Pi8xBV/BIlvi/EjL4x5OuczYnFUtO6iwsSvAJO6OmDG3VkHMo40eeEZZEiXhyczwkEb0pUfzDdf7EBjhRLrl+8H2GMVaUbhu4rhVhNAe4I81mO8nMM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768294931; c=relaxed/simple; bh=nr9/IaOsQYlU/C7lAnMxfez17MlQ2jIUCG6wMu+TG1M=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:To:Cc; b=FawajF4byJGF7EZ94uFAvKcT9O/YIKwVKocGOOwp/NwPavcq1153gL+PfsfYcmeY3S50uaIf8q11VScdldRv+xiY34nPrtzYXfepC0E8itEI79AHTHQouXABT9sv8NxqY90RLAhoxZocG1TgBIg/KTyFfLnq532sgPk+fZ0SNao= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=codeconstruct.com.au; spf=pass smtp.mailfrom=codeconstruct.com.au; dkim=pass (2048-bit key) header.d=codeconstruct.com.au header.i=@codeconstruct.com.au header.b=ROfQah8D; arc=none smtp.client-ip=203.29.241.158 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=codeconstruct.com.au Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=codeconstruct.com.au Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=codeconstruct.com.au header.i=@codeconstruct.com.au header.b="ROfQah8D" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=codeconstruct.com.au; s=2022a; t=1768294903; bh=8Q0eeOz992UGSXugxwAvk0uVEvAvMrcHzJfCBaiSzpY=; h=From:Date:Subject:To:Cc; b=ROfQah8DqvFjaMlXBZRkw6sduPOs7SdiMZTptAUPL1HVekzmdZxrJlUNk9cu1o/bN XaJ2gJteHCs0P2SA1Aiq/FjmhP/NdIdyCvDIdcCkVuq7zXEx2Boko6hh+HgtVTDgjr HHcSwAb7QYewp1YHMwj4bSvJNn0ub4oAuIQUHnVXbD4xrIvLc23GQ72RNAvK6eeDY/ nR2+K2rhiAs0PfDtqwGwWmJsVGrxEnSdGBnuRS4mUL2JGPZpqakRnTcvSUe9f1N5eF NF4NlJgqXnjgmnLRpWuz5E6uv8TOav3wYmjC9vlI4g2TKnBT0OysyUyXQf4Q+5cGwR GH+ktHWgmYYFw== Received: by codeconstruct.com.au (Postfix, from userid 10001) id 9294F6775C; Tue, 13 Jan 2026 17:01:43 +0800 (AWST) From: Matt Johnston Date: Tue, 13 Jan 2026 17:01:16 +0800 Subject: [PATCH net-next] mctp i2c: initialise event handler read bytes Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260113-mctp-read-fix-v1-1-70c4b59c741c@codeconstruct.com.au> X-B4-Tracking: v=1; b=H4sIANsJZmkC/y2OSw7CMAxEr1J5jaO4DdBWCHEP1EVIDASpKSQBF arenfBZjkfznieIHBxHaIsJAj9cdIPPgRYFmLP2J0Znc4ZSlitJVGFv0hUDa4tHNyJTQ9Vyra1 UDeTNNXA+f3l78JzQ85ig+zWBb/csSP/6oCOjGfrepbZ4rAQ1GIz6UHqOUX/VbbH5mWVNkuqyE URKKlUj4evz38VpLypZlbvDM7HV3rDIzC108/wGErWLLt0AAAA= X-Change-ID: 20260113-mctp-read-fix-e191357ad049 To: Jeremy Kerr , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Wolfram Sang Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Andrew Jeffery , Matt Johnston X-Mailer: b4 0.15-dev-cbbb4 X-Developer-Signature: v=1; a=ed25519-sha256; t=1768294902; l=1673; i=matt@codeconstruct.com.au; s=20241018; h=from:subject:message-id; bh=nr9/IaOsQYlU/C7lAnMxfez17MlQ2jIUCG6wMu+TG1M=; b=XNEXjgUx2OEDYxSuNJaeIB6npzDcprMXzwtVo0jM3ac47xPzWjICRSi92H3oL4o1BFu9QEA1l NSGYd1YHBfTD6MxbOT7l1Glaflzb8zps5vseZrudhdwL7aVM2Vx2zck X-Developer-Key: i=matt@codeconstruct.com.au; a=ed25519; pk=exersTcCYD/pEBOzXGO6HkLd6kKXRuWxHhj+LXn3DYE= Set a 0xff value for i2c reads of an mctp-i2c device. Otherwise reads will return "val" from the i2c bus driver. For i2c-aspeed and i2c-npcm7xx that is a stack uninitialised u8. Tested with "i2ctransfer -y 1 r10@0x34" where 0x34 is a mctp-i2c instance, now it returns all 0xff. Fixes: f5b8abf9fc3d ("mctp i2c: MCTP I2C binding driver") Signed-off-by: Matt Johnston --- I'm targeting net-next since this depends on the just-committed fix from Jian Zhang=20 ae4744e173fa ("net: mctp-i2c: fix duplicate reception of old data") That patch and this one should both be applied to stable - will that happen automatically with "Fixes:"? Thanks, Matt --- drivers/net/mctp/mctp-i2c.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/net/mctp/mctp-i2c.c b/drivers/net/mctp/mctp-i2c.c index ecda1cc36391ce50a6b28e6a9e13c3b344f8f993..8043b57bdf25095b3b4e6bacd3a= bbc6f8952acfe 100644 --- a/drivers/net/mctp/mctp-i2c.c +++ b/drivers/net/mctp/mctp-i2c.c @@ -243,7 +243,10 @@ static int mctp_i2c_slave_cb(struct i2c_client *client, =20 switch (event) { case I2C_SLAVE_READ_REQUESTED: + case I2C_SLAVE_READ_PROCESSED: + /* MCTP I2C transport only uses writes */ midev->rx_pos =3D 0; + *val =3D 0xff; break; case I2C_SLAVE_WRITE_RECEIVED: if (midev->rx_pos < MCTP_I2C_BUFSZ) { --- base-commit: f10c325a345fef0a688a2bcdfab1540d1c924148 change-id: 20260113-mctp-read-fix-e191357ad049 prerequisite-message-id: <20260108101829.1140448-1-zhangjian.3032@bytedance= .com> prerequisite-patch-id: 0765450364f2e9f65f6f3940d4a45598763aae8c Best regards, --=20 Matt Johnston