From 3ddee7f88aaf2dee38f7016ac8fd48dd9fdb43e3 Mon Sep 17 00:00:00 2001 From: Baolin Wang Date: Tue, 24 Apr 2018 20:06:11 +0800 Subject: ALSA: Avoid using timespec for struct snd_pcm_status The struct snd_pcm_status will use 'timespec' type variables to record timestamp, which is not year 2038 safe on 32bits system. Userspace will use SNDRV_PCM_IOCTL_STATUS and SNDRV_PCM_IOCTL_STATUS_EXT as commands to issue ioctl() to fill the 'snd_pcm_status' structure in userspace. The command number is always defined through _IOR/_IOW/IORW, so when userspace changes the definition of 'struct timespec' to use 64-bit types, the command number also changes. Thus in the kernel, we now need to define two versions of each such ioctl and corresponding ioctl commands to handle 32bit time_t and 64bit time_t in native mode: struct snd_pcm_status32 { ...... s32 trigger_tstamp_sec; s32 trigger_tstamp_nsec; ...... s32 audio_tstamp_sec; s32 audio_tstamp_nsec; ...... }; struct snd_pcm_status64 { ...... s32 trigger_tstamp_sec; s32 trigger_tstamp_nsec; ...... s32 audio_tstamp_sec; s32 audio_tstamp_nsec; ...... }; Moreover in compat file, we renamed or introduced new structures to handle 32bit/64bit time_t in compatible mode. The 'struct snd_pcm_status32' and snd_pcm_status_user32() are used to handle 32bit time_t in compat mode. 'struct compat_snd_pcm_status64' and snd_pcm_status_user_compat64() are used to handle 64bit time_t. The implicit padding before timespec is made explicit to avoid incompatible structure layout between 32-bit and 64-bit x86 due to the different alignment requirements, and the snd_pcm_status structure is now hidden from the kernel to avoid relying on the timespec definitio definitionn Finally we can replace SNDRV_PCM_IOCTL_STATUS and SNDRV_PCM_IOCTL_STATUS_EXT with new commands and introduce new functions to fill new 'struct snd_pcm_status64' instead of using unsafe 'struct snd_pcm_status'. Then in future, the new commands can be matched when userspace changes 'timespec' to 64bit type to make a size change of 'struct snd_pcm_status'. When glibc changes time_t to 64-bit, any recompiled program will issue ioctl commands that the kernel does not understand without this patch. Signed-off-by: Baolin Wang Signed-off-by: Arnd Bergmann --- include/uapi/sound/asound.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/uapi/sound') diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h index 40a23d8418fe..d2c88c098b20 100644 --- a/include/uapi/sound/asound.h +++ b/include/uapi/sound/asound.h @@ -456,8 +456,13 @@ enum { SNDRV_PCM_AUDIO_TSTAMP_TYPE_LAST = SNDRV_PCM_AUDIO_TSTAMP_TYPE_LINK_SYNCHRONIZED }; +#ifndef __KERNEL__ +/* explicit padding avoids incompatibility between i386 and x86-64 */ +typedef struct { unsigned char pad[sizeof(time_t) - sizeof(int)] __time_pad; + struct snd_pcm_status { snd_pcm_state_t state; /* stream state */ + __time_pad pad1; /* align to timespec */ struct timespec trigger_tstamp; /* time when stream was started/stopped/paused */ struct timespec tstamp; /* reference timestamp */ snd_pcm_uframes_t appl_ptr; /* appl ptr */ @@ -473,6 +478,7 @@ struct snd_pcm_status { __u32 audio_tstamp_accuracy; /* in ns units, only valid if indicated in audio_tstamp_data */ unsigned char reserved[52-2*sizeof(struct timespec)]; /* must be filled with zero */ }; +#endif struct snd_pcm_mmap_status { snd_pcm_state_t state; /* RO: state - SNDRV_PCM_STATE_XXXX */ -- cgit v1.2.3