From: Benoit Sevens <bsevens@google.com>
To: Rishi Gupta <gupt21@gmail.com>, Jiri Kosina <jikos@kernel.org>,
Benjamin Tissoires <bentiss@kernel.org>
Cc: linux-i2c@vger.kernel.org, linux-input@vger.kernel.org,
linux-kernel@vger.kernel.org,
"Benoît Sevens" <bsevens@google.com>
Subject: [PATCH] HID: mcp2221: Fix heap buffer overflow in mcp2221_raw_event()
Date: Wed, 15 Apr 2026 11:47:51 +0000 [thread overview]
Message-ID: <20260415114752.1181079-1-bsevens@google.com> (raw)
From: Benoît Sevens <bsevens@google.com>
A heap buffer overflow can occur in the mcp2221_raw_event() function
when handling I2C read responses. The driver failed to check if the
total incoming data length fits within the originally allocated buffer
`mcp->rxbuf`.
Fix this by introducing `rxbuf_len` to `struct mcp2221` to keep track
of the allocated buffer size. Initialize it in `mcp_i2c_smbus_read()`
and `mcp_smbus_xfer()`, and ensure the copied data length combined with
the current index does not exceed this length in `mcp2221_raw_event()`.
Signed-off-by: Benoît Sevens <bsevens@google.com>
---
drivers/hid/hid-mcp2221.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/hid/hid-mcp2221.c b/drivers/hid/hid-mcp2221.c
index ef3b5c77c38e..744561e65079 100644
--- a/drivers/hid/hid-mcp2221.c
+++ b/drivers/hid/hid-mcp2221.c
@@ -119,6 +119,7 @@ struct mcp2221 {
struct completion wait_in_report;
struct delayed_work init_work;
u8 *rxbuf;
+ int rxbuf_len;
u8 txbuf[64];
int rxbuf_idx;
int status;
@@ -323,12 +324,14 @@ static int mcp_i2c_smbus_read(struct mcp2221 *mcp,
mcp->txbuf[3] = (u8)(msg->addr << 1);
total_len = msg->len;
mcp->rxbuf = msg->buf;
+ mcp->rxbuf_len = msg->len;
} else {
mcp->txbuf[1] = smbus_len;
mcp->txbuf[2] = 0;
mcp->txbuf[3] = (u8)(smbus_addr << 1);
total_len = smbus_len;
mcp->rxbuf = smbus_buf;
+ mcp->rxbuf_len = smbus_len;
}
ret = mcp_send_data_req_status(mcp, mcp->txbuf, 4);
@@ -538,6 +541,7 @@ static int mcp_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
mcp->rxbuf_idx = 0;
mcp->rxbuf = data->block;
+ mcp->rxbuf_len = sizeof(data->block);
mcp->txbuf[0] = MCP2221_I2C_GET_DATA;
ret = mcp_send_data_req_status(mcp, mcp->txbuf, 1);
if (ret)
@@ -561,6 +565,7 @@ static int mcp_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
mcp->rxbuf_idx = 0;
mcp->rxbuf = data->block;
+ mcp->rxbuf_len = sizeof(data->block);
mcp->txbuf[0] = MCP2221_I2C_GET_DATA;
ret = mcp_send_data_req_status(mcp, mcp->txbuf, 1);
if (ret)
@@ -908,7 +913,9 @@ static int mcp2221_raw_event(struct hid_device *hdev,
}
if (data[2] == MCP2221_I2C_READ_COMPL ||
data[2] == MCP2221_I2C_READ_PARTIAL) {
- if (!mcp->rxbuf || mcp->rxbuf_idx < 0 || data[3] > 60) {
+ if (!mcp->rxbuf || mcp->rxbuf_idx < 0 ||
+ data[3] > 60 ||
+ mcp->rxbuf_idx + data[3] > mcp->rxbuf_len) {
mcp->status = -EINVAL;
break;
}
--
2.54.0.rc0.605.g598a273b03-goog
reply other threads:[~2026-04-15 11:48 UTC|newest]
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