Possible memory leak in cafe_ccic.ko

[Anton Volkov]

Hello.

While searching for races in the Linux kernel I've come across 
"drivers/media/platform/marvell-ccic/cafe_ccic.ko" module. Here are 
questions that I came up with while analyzing results. Lines are given 
using the info from Linux v4.12.

Consider the following case:

Thread 1:                  Thread 2:
                           mcam_v4l_release
                           ->mcam_free_dma_bufs
                               cam->dma_bufs[i] = NULL
                               cam->nbufs = 0
cafe_pci_resume                (mcam-core.c: line 413)
->mccic_resume
  ->mcam_read_setup
    ->mcam_alloc_dma_bufs
      cam->dma_bufs[i] =
         dma_alloc_coherent()
         (mcam-core.c: line 381)

It looks like mcam_v4l_release() doesn't really shut the device down. In 
this case cafe_pci_resume() leaks memory for cam->dma_bufs[i] after 
mcam_v4l_release() freed and poisoned them. Is this feasible from your 
point of view?

Thank you for your time.

-- Anton Volkov
Linux Verification Center, ISPRAS
web: http://linuxtesting.org
e-mail: avolkov@xxxxxxxxx