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 90C5C438470 for ; Mon, 7 Sep 2026 22:12:44 +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=1788819165; cv=none; b=HvwfKomGoLf6D98B1qPPa3LA4zC5nf7/e5KewD5xvjuil7A/9mWNWo9ADh5DNeURn+6a/PTbI3YZA3xniBC/X2HPRJPwqb+vJiHH+h69RxrdeHzd7OzDaCbpdpcpkuNd71igL3sNxM/Ei1uRCPblLUEIxXZCp3Rh1DXqga0wt1g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788819165; c=relaxed/simple; bh=tJoWjNcoufSUMa7Ew+vjXF8Z4p8XJdGtM7HBcMDSeic=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=bnXcWLLR4kqfQ03GKLVP1rgFgo3zoSxaLVPNXxWjipH355Rjm9qQZ32iiZWoilx5hnd/8dPsf7EkSXloV40ZZfXZ6z2uLu4BCf9kNJUvDTSiSjfsHP80308mT2hiUXrZo2a8miArIXNO4Zq8cj6tgn0G/CHn7zub5rnsl8xwpuU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZScoIo/K; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZScoIo/K" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CCEB81F00A3D; Mon, 7 Sep 2026 22:12:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788819164; bh=mbtXrd3+RAJ4Nbe+DVp1B9jSEdzSlYRWNfZwJDJGD2M=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ZScoIo/KlbYjoozuXVVOoGqX6LVXQbvpND7M4CLgcp4J9vdogk1cwtru/crDlVtKV HmpbD6djhTWC+EXjkUi9H2AU2kt/igPKVuuLRZHb7PbMdI9mKay1XuSVb+XQAYFdVZ CGP7/zkYKUttfX9N/mArGK0WsD/OHKn/GM13GvlpWsItTJ0/O+ZapcTkNq8AXBUR6l O1rSvNs1iRGCiTsC2CbSUeH/xWmkV/dYsFgzsotf4Lyq2jGW5n77b/5JZ/dPULVmjt 3pz4922vbXD7CeufCxCUMvCWO4mVv89lSHNCpNGhRJsSOieIXQ3s5Rt2faRpyV8mvY U5XPtC+IDTo/Q== From: Sasha Levin To: stable@vger.kernel.org Cc: Jiangshan Yi , Jiri Kosina , Sasha Levin Subject: [PATCH 5.15.y 2/2] HID: mcp2221: clear rxbuf after I2C/SMBus transfer completes Date: Mon, 7 Sep 2026 18:12:41 -0400 Message-ID: <20260907221241.650068-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260907221241.650068-1-sashal@kernel.org> References: <2026090357-unleash-dimple-e652@gregkh> <20260907221241.650068-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Jiangshan Yi [ Upstream commit db2333f88729c8aae062cb171ed058725ff5c901 ] mcp_i2c_smbus_read() stores the caller-supplied buffer pointer in mcp->rxbuf for the duration of a transfer but never clears it when the transfer finishes or times out. Once the caller frees or reuses the buffer, mcp->rxbuf becomes a dangling pointer. A delayed or spurious MCP2221_I2C_GET_DATA report can then drive mcp2221_raw_event() to memcpy device data into the freed memory, causing a write use-after-free. Route all return paths through a single exit point that clears mcp->rxbuf and mcp->rxbuf_size, so that the existing !mcp->rxbuf guard in the raw_event handler can reject any report arriving after the transfer has ended. Fixes: 67a95c21463d ("HID: mcp2221: add usb to i2c-smbus host bridge") Cc: stable@vger.kernel.org Signed-off-by: Jiangshan Yi Signed-off-by: Jiri Kosina Signed-off-by: Sasha Levin --- drivers/hid/hid-mcp2221.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/hid/hid-mcp2221.c b/drivers/hid/hid-mcp2221.c index 239efb89490f9..d824e5b945458 100644 --- a/drivers/hid/hid-mcp2221.c +++ b/drivers/hid/hid-mcp2221.c @@ -302,7 +302,7 @@ static int mcp_i2c_smbus_read(struct mcp2221 *mcp, ret = mcp_send_data_req_status(mcp, mcp->txbuf, 4); if (ret) - return ret; + goto out; mcp->rxbuf_idx = 0; @@ -324,7 +324,7 @@ static int mcp_i2c_smbus_read(struct mcp2221 *mcp, } else { usleep_range(980, 1000); mcp_cancel_last_cmd(mcp); - return ret; + goto out; } } else { retries = 0; @@ -334,6 +334,10 @@ static int mcp_i2c_smbus_read(struct mcp2221 *mcp, usleep_range(980, 1000); ret = mcp_chk_last_cmd_status_free_bus(mcp); +out: + mcp->rxbuf = NULL; + mcp->rxbuf_size = 0; + return ret; } -- 2.53.0