media: rtl2832_sdr: release URBs and stream buffers on start_streaming() failure

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rtl2832_sdr_start_streaming() calls rtl2832_sdr_alloc_stream_bufs(),
rtl2832_sdr_alloc_urbs() and rtl2832_sdr_submit_urbs() in sequence and
shares a single err: label that only unlocks the mutex and returns.
When alloc_urbs() succeeds but submit_urbs() fails, or when alloc_urbs()
itself returns -ENOMEM after alloc_stream_bufs() has already succeeded,
the URBs and/or the coherent DMA stream buffers stay allocated while
streaming reports failure to vb2. Two latent defects follow on the next
VIDIOC_STREAMON:

1) rtl2832_sdr_alloc_stream_bufs() unconditionally resets dev->buf_num
   to 0 and overwrites dev->buf_list[]/dev->dma_addr[], permanently
   leaking the coherent DMA memory allocated by the previous attempt.

2) rtl2832_sdr_alloc_urbs() never resets dev->urbs_initialized and only
   increments it. After a second successful pass urbs_initialized can
   exceed MAX_BULK_BUFS, so the subsequent rtl2832_sdr_free_urbs() walks
   from urbs_initialized - 1 down to 0 and reads past the end of
   dev->urb_list[], passing garbage pointers to usb_free_urb().

Mirror the teardown that stop_streaming() already performs: on the error
path call rtl2832_sdr_free_urbs() and rtl2832_sdr_free_stream_bufs()
before unlocking. Both helpers are idempotent (free_urbs kills and zeros
urbs_initialized; free_stream_bufs is gated on URB_BUF and clears the
buf_num counter), so partial-failure paths and the no-allocation paths
remain safe.

Issue identified by automated review of the INV-003 series at
https://sashiko.dev/

Fixes: 771138920e ("[media] rtl2832_sdr: Realtek RTL2832 SDR driver module")
Cc: stable@vger.kernel.org
Signed-off-by: Valery Borovsky <vebohr@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>

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Valery Borovsky 2026-05-23 19:53:58 +03:00 • committed by Hans Verkuil

parent 2f378dc45e

commit fe50cdaebf

1 changed files with 3 additions and 0 deletions

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drivers/media/dvb-frontends/rtl2832_sdr.c

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