In the Linux kernel, the following vulnerability has been resolved:
media: msi2500: Return queued buffers on start_streaming() failure
The vb2 framework hands buffers to the driver via buf_queue() before calling start_streaming(). If start_streaming() returns an error without first returning those buffers via vb2_buffer_done(), vb2_start_streaming() fires WARN_ON(owned_by_drv_count) and the queued buffers leak.
msi2500_start_streaming() had five error paths that all hit this trap and were further tangled by ret-overwriting between calls:
- -ENODEV when the USB device was already disconnected
- -ERESTARTSYS when mutex_lock_interruptible() was interrupted
- msi2500_set_usb_adc() failure: ret was silently overwritten by the next call (msi2500_isoc_init), so the error was lost entirely
- msi2500_isoc_init() failure: cleanup_queued_bufs was called, but the function then fell through to msi2500_ctrl_msg() and again masked the original error by overwriting ret
- msi2500_ctrl_msg(CMD_START_STREAMING) failure: no cleanup at all, leaving isoc URBs submitted with no way for the driver to consume them
Consolidate the error paths into a small goto chain. Every failure now stops the function, drains the queued-buffer list, and returns the real error code. The ctrl_msg failure path also rolls back the preceding msi2500_isoc_init() via msi2500_isoc_cleanup() before unlocking and draining.
The cleanup helper takes a vb2_buffer_state argument so that the start_streaming error paths can pass VB2_BUF_STATE_QUEUED (as expected by userspace on start_streaming failure) while stop_streaming keeps its existing VB2_BUF_STATE_ERROR semantics.
This mirrors the uvcvideo fix in commit 4cf3b6fd54eb (media: uvcvideo: Return queued buffers on start_streaming() failure).
References
- https://git.kernel.org/stable/c/1d58229b330b7f67fbfa07e0f2a8a51fbeafaa9a
- https://git.kernel.org/stable/c/264b5380c4f8aa92dbc2983ecd2b627f1d5e0061
- https://git.kernel.org/stable/c/3673cb0a5711e910074d69201da9e1535c03f97a
- https://git.kernel.org/stable/c/7201c17786a498497bca57752883b90914d405ac
- https://git.kernel.org/stable/c/bab9d5a67d4db96ae8c187b92b37979911302a10