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 A386F3546C1 for ; Mon, 7 Sep 2026 22:07:24 +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=1788818845; cv=none; b=o4Mk/gnd8kwpKUC5hrYXvqLwrOvDjZ4ULdya3bv5fWw9WFuRgQ1xnEpKcGog3X8zJ98tEJPOLhYoSxNWv+03/HoL1UyJgc7MSWZq3QFnkrq+fhl5N1bH5CP2lKo7lhbRwAI0WYuH4ScaUgjfGOohkKc0NPzivPxr5vWMHnV6vpc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788818845; c=relaxed/simple; bh=y8R91NqxziWrSYcBTpRJQsjckvg81+i3yriWO78DF6w=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=f9d/hBmi4eMaIDzNRZ00LWPBE3BHhWk9M0kFBhm5vsag5F8x1FfP8drDcSv4ofKYo2l9P/zlg1GZdUjCm6II6aslFjEr3Rdc1C4g0G/h3oS0s+FcI3Tpw0J8RJDa+K/Jw6bRoRFm8oizbMBR0bPmDmVW+/Wt/YP8iTplyXSNCTI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nE5XU4xJ; 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="nE5XU4xJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 03D001F00A3D; Mon, 7 Sep 2026 22:07:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788818844; bh=JtXREQJdWDy6KnOyMuznLFHne316ueGPWeFi2TEi0sw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=nE5XU4xJoC9pflk9ecNWPkF7my6WKXC24ZzQJWZomSbBb2PyP9+hxnckcdvgzsqtI bkfwm2/n76hUmSyNBAI7GSekuze56L19QkusUO1FBHyktSzaktQBDm4ohirw/a27cR u13r8ZTEulSaobrVaHFl3UMA5fhbCY62XTd9GWl2oUr7RQBKJSq8T8zezOEbqhD1yY OhKcOmwF5j+Ruihs6u+5lLzKWEnDlj8eNGCudrIvkqNQQ447tW4+AtBh/2tfM5ZI7U kI4SJNF2fAAv/9I7pka2v1x0z4z8HVvbgd6mJWjx4vrc9Of7rF5SntyKluw4jSOoYe ZRX/VPe7ks/xQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Jiangshan Yi , Jiri Kosina , Sasha Levin Subject: [PATCH 6.1.y 2/2] HID: mcp2221: clear rxbuf after I2C/SMBus transfer completes Date: Mon, 7 Sep 2026 18:07:21 -0400 Message-ID: <20260907220721.641617-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260907220721.641617-1-sashal@kernel.org> References: <2026090357-reference-varied-a710@gregkh> <20260907220721.641617-1-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 f041e47ffba1e..2332ce6cf5cc5 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