5.15-stable review patch. If anyone has any objections, please let me know.
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From: Arnaud Lecomte contact@arnaud-lcm.com
commit b56cc41a3ae7323aa3c6165f93c32e020538b6d2 upstream.
As reported by syzbot, mcp2221_raw_event lacked validation of incoming I2C read data sizes, risking buffer overflows in mcp->rxbuf during multi-part transfers. As highlighted in the DS20005565B spec, p44, we have: "The number of read-back data bytes to follow in this packet: from 0 to a maximum of 60 bytes of read-back bytes." This patch enforces we don't exceed this limit.
Reported-by: syzbot+52c1a7d3e5b361ccd346@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=52c1a7d3e5b361ccd346 Tested-by: syzbot+52c1a7d3e5b361ccd346@syzkaller.appspotmail.com Signed-off-by: Arnaud Lecomte contact@arnaud-lcm.com Link: https://patch.msgid.link/20250726220931.7126-1-contact@arnaud-lcm.com Signed-off-by: Benjamin Tissoires bentiss@kernel.org Signed-off-by: Romain Sioen romain.sioen@microchip.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/hid/hid-mcp2221.c | 4 ++++ 1 file changed, 4 insertions(+)
--- a/drivers/hid/hid-mcp2221.c +++ b/drivers/hid/hid-mcp2221.c @@ -791,6 +791,10 @@ static int mcp2221_raw_event(struct hid_ } if (data[2] == MCP2221_I2C_READ_COMPL || data[2] == MCP2221_I2C_READ_PARTIAL) { + if (!mcp->rxbuf || mcp->rxbuf_idx < 0 || data[3] > 60) { + mcp->status = -EINVAL; + break; + } buf = mcp->rxbuf; memcpy(&buf[mcp->rxbuf_idx], &data[4], data[3]); mcp->rxbuf_idx = mcp->rxbuf_idx + data[3];