ASoC: stm32: spdifrx: fix dma channel release in stm32_spdifrx_remove

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: ASoC: stm32: spdifrx: fix dma channel release in stm32_spdifrx_remove In case of error when requesting ctrl_chan DMA channel, ctrl_chan is not null. So the release of the dma channel leads to the following issue: [ 4.879000] st,stm32-spdifrx 500d0000.audio-controller: dma_request_slave_channel error -19 [ 4.888975] Unable to handle kernel NULL pointer dereference at virtual address 000000000000003d [...] [ 5.096577] Call trace: [ 5.099099] dma_release_channel+0x24/0x100 [ 5.103235] stm32_spdifrx_remove+0x24/0x60 [snd_soc_stm32_spdifrx] [ 5.109494] stm32_spdifrx_probe+0x320/0x4c4 [snd_soc_stm32_spdifrx] To avoid this issue, release channel only if the pointer is valid.

References

• https://git.kernel.org/stable/c/3a977b554f668382dfba31fd62e4cce4fe5643db
• https://git.kernel.org/stable/c/0d75f887aabd80cf37ea48d28f159afa7850ea28
• https://git.kernel.org/stable/c/4f1d74f74752eab8af6b8b28797dc6490d57374c
• https://git.kernel.org/stable/c/23bdbd1ef3e063e03d3c50c15a591b005ebbae39
• https://git.kernel.org/stable/c/22ae9321054cf7f36c537702af133659f51a0b88
• https://git.kernel.org/stable/c/9bb4af400c386374ab1047df44c508512c08c31f