HID: ft260: fix stack-use-after-return write in I2C read race

ft260_i2c_read() points dev->read_buf at a caller-supplied buffer
(often an on-stack variable), arms a completion and waits up to five
seconds for the device to return the data. The HID input callback
ft260_raw_event() runs in the input/IRQ path, independent of the
dev->lock mutex held by the read path, and copies the device-supplied
payload into dev->read_buf after a plain NULL check.

These two paths share read_buf, read_idx and read_len with no
serialization. If the device delays its response until the read
times out, ft260_i2c_read() resets the controller, clears read_buf
and returns, unwinding the stack frame the buffer lived in. A
response that arrives at that moment lets ft260_raw_event() pass the
NULL check and then memcpy() the device-controlled payload into the
now-freed stack location, a bounded but attacker-influenced
stack-use-after-return write triggerable by malicious or
malfunctioning hardware.

Add a dedicated spinlock that serializes every access to read_buf,
read_idx and read_len. ft260_raw_event() now holds it across the
NULL check, the memcpy and the index update, while the read path
takes it when arming and when clearing the buffer, so the teardown
can no longer slip between the check and the copy.

Fixes: 6a82582d9fa4 ("HID: ft260: add usb hid to i2c host bridge driver")
Cc: stable@vger.kernel.org
Signed-off-by: Raman Varabets <kernel-linux-20260610-80b7ab08@raman.v1.sg>
Reviewed-by: Michael Zaidman <michael.zaidman@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>

0 files changed, 0 insertions, 0 deletions