ASoC: dapm: Fix UAF for snd_soc_pcm_runtime object

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: ASoC: dapm: Fix UAF for snd_soc_pcm_runtime object When using kernel with the following extra config, - CONFIG_KASAN=y - CONFIG_KASAN_GENERIC=y - CONFIG_KASAN_INLINE=y - CONFIG_KASAN_VMALLOC=y - CONFIG_FRAME_WARN=4096 kernel detects that snd_pcm_suspend_all() access a freed 'snd_soc_pcm_runtime' object when the system is suspended, which leads to a use-after-free bug: [ 52.047746] BUG: KASAN: use-after-free in snd_pcm_suspend_all+0x1a8/0x270 [ 52.047765] Read of size 1 at addr ffff0000b9434d50 by task systemd-sleep/2330 [ 52.047785] Call trace: [ 52.047787] dump_backtrace+0x0/0x3c0 [ 52.047794] show_stack+0x34/0x50 [ 52.047797] dump_stack_lvl+0x68/0x8c [ 52.047802] print_address_description.constprop.0+0x74/0x2c0 [ 52.047809] kasan_report+0x210/0x230 [ 52.047815] __asan_report_load1_noabort+0x3c/0x50 [ 52.047820] snd_pcm_suspend_all+0x1a8/0x270 [ 52.047824] snd_soc_suspend+0x19c/0x4e0 The snd_pcm_sync_stop() has a NULL check on 'substream->runtime' before making any access. So we need to always set 'substream->runtime' to NULL everytime we kfree() it.

References

• https://git.kernel.org/stable/c/993b60c7f93fa1d8ff296b58f646a867e945ae89
• https://git.kernel.org/stable/c/8ca21e7a27c66b95a4b215edc8e45e5d66679f9f
• https://git.kernel.org/stable/c/3033ed903b4f28b5e1ab66042084fbc2c48f8624
• https://git.kernel.org/stable/c/fe5046ca91d631ec432eee3bdb1f1c49b09c8b5e
• https://git.kernel.org/stable/c/5d13afd021eb43868fe03cef6da34ad08831ad6d
• https://git.kernel.org/stable/c/6a14fad8be178df6c4589667efec1789a3307b4e
• https://git.kernel.org/stable/c/b4a90b543d9f62d3ac34ec1ab97fc5334b048565