commit e199bf52ffda8f98f129728d57244a9cd9ad5623 upstream.
If bus is marked as multi_link, but number of masters in the stream is
not higher than bus->hw_sync_min_links (bus->multi_link && m_rt_count >=
bus->hw_sync_min_links), bank switching should not happen. The first
part of do_bank_switch() code properly takes these conditions into
account, but second part (sdw_ml_sync_bank_switch()) relies purely on
bus->multi_link property. This is not balanced and leads to NULL
pointer dereference:
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
...
Call trace:
wait_for_completion_timeout+0x124/0x1f0
do_bank_switch+0x370/0x6f8
sdw_prepare_stream+0x2d0/0x438
qcom_snd_sdw_prepare+0xa0/0x118
sm8450_snd_prepare+0x128/0x148
snd_soc_link_prepare+0x5c/0xe8
__soc_pcm_prepare+0x28/0x1ec
dpcm_be_dai_prepare+0x1e0/0x2c0
dpcm_fe_dai_prepare+0x108/0x28c
snd_pcm_do_prepare+0x44/0x68
snd_pcm_action_single+0x54/0xc0
snd_pcm_action_nonatomic+0xe4/0xec
snd_pcm_prepare+0xc4/0x114
snd_pcm_common_ioctl+0x1154/0x1cc0
snd_pcm_ioctl+0x54/0x74
Fixes: ce6e74d008ff ("soundwire: Add support for multi link bank switch")
Cc: stable@vger.kernel.org
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20231124180136.390621-1-krzysztof.kozlowski@linaro.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
03048a9ba3