linux-loongson/drivers/media/cec/usb
Gui-Dong Han 7af160aea2 media: rainshadow-cec: fix TOCTOU race condition in rain_interrupt()
In the interrupt handler rain_interrupt(), the buffer full check on
rain->buf_len is performed before acquiring rain->buf_lock. This
creates a Time-of-Check to Time-of-Use (TOCTOU) race condition, as
rain->buf_len is concurrently accessed and modified in the work
handler rain_irq_work_handler() under the same lock.

Multiple interrupt invocations can race, with each reading buf_len
before it becomes full and then proceeding. This can lead to both
interrupts attempting to write to the buffer, incrementing buf_len
beyond its capacity (DATA_SIZE) and causing a buffer overflow.

Fix this bug by moving the spin_lock() to before the buffer full
check. This ensures that the check and the subsequent buffer modification
are performed atomically, preventing the race condition. An corresponding
spin_unlock() is added to the overflow path to correctly release the
lock.

This possible bug was found by an experimental static analysis tool
developed by our team.

Fixes: 0f314f6c2e ("[media] rainshadow-cec: new RainShadow Tech HDMI CEC driver")
Cc: stable@vger.kernel.org
Signed-off-by: Gui-Dong Han <hanguidong02@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
2025-06-17 10:35:16 +02:00
..
extron-da-hd-4k-plus media: cec: extron-da-hd-4k-plus: Fix Wformat-truncation 2025-04-25 15:14:30 +02:00
pulse8 media: pulse8-cec: fix data timestamp at pulse8_setup() 2024-10-18 10:43:03 +02:00
rainshadow media: rainshadow-cec: fix TOCTOU race condition in rain_interrupt() 2025-06-17 10:35:16 +02:00
Kconfig media: cec: extron-da-hd-4k-plus: add the Extron DA HD 4K Plus CEC driver 2024-09-05 20:13:41 +02:00
Makefile media: cec: extron-da-hd-4k-plus: add the Extron DA HD 4K Plus CEC driver 2024-09-05 20:13:41 +02:00